Component is not reading object value from a const - reactjs

I am trying to pass value from const options to a component. Am I doing everything right?When I try to read the props in child component I just get get value="undefined". I am just trying to pass options.value to FetchRandomBet in order to use options.value in a child component.
import React, { Component } from 'react';
import Select from 'react-select';
import Button from '#material-ui/core/Button';
import FetchRandomBet from "./fetchRandomBets";
const options = [
{ value: '1', label: 'less than 2' },
{ value: '2', label: 'more than 2' },
];
class Betslip extends Component {
state = {
names: [],
odds: []
};
render() {
return (
<div className="betslip">
<div className="betslip-top">
<h1 className="text">BETSLIP</h1>
<p className="text-two">BET WITH US!</p>
<Select className="filter-menu" options={options} />
</div>
<div>
<FetchRandomBet
key={options.value}
value={options.value} />
</div>
console.log(options.value)
<Button className="betnow" variant="contained">
Bet Now!
</Button>
</div>
);
}
}
export default Betslip;

options is an array of object, so you can't use options.value. You must go to the array element and then do .value on that, i.e., options[0].value, options[1].value.
It also depends on how FetchRandomBet component is accepting the props. If value props of FetchRandomBet is designed to accept array then, you just pass whole options like below code:
<div>
<FetchRandomBet key={1} value={options} />
</div>
Note: This is assuming your FetchRandomBet component accepts value as array.
Or if you want to call FetchRandomBet for each of the options value (which is highly unlikely with the context you provided in your question), you can do something like this:
<div>
{
options.map(option => <FetchRandomBet key={option.value} value={option.value} />)
}
</div>
The above code will create instances of FetchRandomBet for each of the option values.

First you should not console.log inside the return statement, but its okay outside.
Next try to use this
const value = options.map((op) => op.value)
const label = options.map((op) => op.label)
<FetchRandomBet
key={value}
value={label} />
You are acessing an array like if its an object so first you should enter the object and then select the key or the value.
In this way you will pass to the child component two array:
value = [1,2]
label = ["less than 2", "more than 2"]
Let me know if its what u were looking for

Related

How to check if all instances of a React Component have the same value for their state?

So right now, in my App file I have this:
{items.map(el => (
<Item
prop1={foo}
prop2={bar}
el={baz}
/>
))}
And in the <Item> component, I have this:
<span className={finishedClass ? "finishedItem" : ""}>
{props.el}
</span>
where finishedClass is a state variable.
So my question is, how can I check if finishedClass is true for every single <Item> component that gets generated as a result of the items.map?
So, you basically want to know if all the finishedClass state values in all the Item components are true. This can be simplified in the sense that if any of the Item components have finishedClass as false, you will perform a certain action.
So, what you can do is, pass a function as a prop to the Item component as follows:
{items.map(el => (
<Item
prop1={foo}
prop2={bar}
el={baz}
setFinishedClassToFalse={()=>{/*your statements*/}}
/>
))}
This function setFinishedClassToFalse will be called by the Item component if and only if its state value finishedClass is false. Obviously, there's a little more implementation to this than what I have described. But this should give you a start.
Parent component can communication with child component with parent props that have function in it. You can see code below onFinished property in Parent component has handleFinished() function value in it. That fucntion will be a bridge to help Child component to communicate with Parent component. On the Child component you must run onFinished props to triggering handleFinished function on Parent comoponent. In code below the trigger for props.onFinished is when <span> clicked by user.
import React from "react";
import ReactDOM from "react-dom";
import { Grid } from "react-flexbox-grid";
class App extends React.Component {
constructor(props) {
super(props);
this.state = { data: "test" };
}
render() {
const items = ["red", "green", "blue"];
const handleFinished = (e, index) => {
this.setState({ data: e });
console.log(this.state);
};
return (
<Grid>
{items.map((el, index) => (
<Child
prop1={"test"}
prop2={"test1"}
el={el}
onFinished={(e) => handleFinished(e, index)}
/>
))}
<div>{this.state.data.toString()}</div>
</Grid>
);
}
}
const Child = (props) => {
// example for your finishedClass value state
const finishedClass = true;
return (
<span
onClick={() => props.onFinished(finishedClass)}
className={finishedClass ? "finishedItem" : ""}
>
{props.el}{" "}
</span>
);
};
ReactDOM.render(<App />, document.getElementById("container"));
As finishedClass is a state variable, if you just console.log(finishedClass) inside component it will just do the work

React redux saga multiple renders

I'm new to react and I'm having an issue of multiple renders and I was just wondering if I'm doing this right, so I dispatched an action to get a note list, in my list component which looks like this for now :
import React, {useState, useEffect} from 'react';
export default function NoteList (props){
const [ noteList, updateNoteList ] = useState([]);
useEffect(()=>{
updateNoteList(
props.noteList.map(note => {
return {...note, mode : 'title-mode'};
})
)
},[props.noteList])
console.log(noteList);
return (
<div>
Notes come here
</div>
)
}
this component is connected in another container class but that's irrelevant, so what happens is this component renders 4 times, two times without the useEffect hook and two more with it, what I want to achieve is I need to add an item in the object of each note (which is mode : title-mode) in a state for this component which works fine with this code, as to why I'm adding this mode in a state is that I want to change this inside the note array so I can change the view mode for each note , but this component renders 4 times as I mentioned, and in my head no way that this is the correct way to do this.
Please help if you have the time .
We could achieve the display of the notes list by making a display-mode state in the <Note /> component it self so changing the mode won't affect other notes and this way we won't have extra re-renders, also using this approach will allow also modifying the note locally without dispatching it to the store then we could update the store at the end gaining in perfs.
So basically this is the approach (codesandbox):
const Note = ({ title, content }) => {
const [isExpanded, setIsExpanded] = useState(false);
return (
<div
style={{ border: "1px solid", margin: 5 }}
onClick={() => setIsExpanded(!isExpanded)}
>
{!isExpanded ? (
<div>
<h2>{title}</h2>
</div>
) : (
<div>
<h2>{title}</h2>
<p>{content}</p>
</div>
)}
</div>
);
};
function App() {
// this is the notes state, it could be coming from redux store so
// we could interact with it (modifying it if we need)
const [notes, setNotes] = React.useState([
{ id: 1, title: "note 1", content: "this is note 1" },
{ id: 2, title: "note 2", content: "this is note 2" }
]);
return (
<div className="App">
{notes.map((note) => (
<Note key={note.id} {...note} />
))}
</div>
);
}

Render map not displaying data on screen

I can't seem to get my renderJob mapping to render out properly. I have no errors in the console and can't figure out while nothing is showing up. Is there a problem with the way I'm mapping the object to the index?
import React, { Component } from 'react'
import PropTypes from 'prop-types'
const jbSampleData = [
{
name: 'A place',
location: 'USA',
engineer: "Contact Engineer",
service: "Last install"
},
]
class Job extends Component {
render() {
const renderJob = this.props.data.map((obj, idx) => {
return (
<div key={idx}>
<div>
<p>
<span>Name:</span> {obj.name} < br/>
<span>Location:</span> {obj.location} <br />
<span>Engineer Contact:</span> {obj.engineer} <br />
<span>Service:</span> {obj.service} <br />
</p>
</div>
</div>
);
});
return (
<div>
<renderJob />
Hello
</div>
)
}
}
Job.propTypes = {
data: PropTypes.arrayOf(
PropTypes.object
)
}
Job.defaultProps = {
data: jbSampleData
}
export default Job;
You are storing the map result basically an array in a variable renderJob, that is not a react component.
You need to render it like this:
return (
<div>
{renderJob}
Hello
</div>
)
Basically <renderJob> will get converted into:
React.createElement(renderJob, null); //new custom element
But in case of {renderJob} its value will get replaced, and all the ui items that variable is having will get rendered.
Why it is not throwing the error with <renderJob/> ?
Because name is stated with small letter so it will be considered as a built-in component like div etc, if you use <RenderJob/> it will throw error that RenderJob is not defined.
As per DOC:
When an element type starts with a lowercase letter, it refers to a
built-in component like <div> or <span> and results in a string 'div'
or 'span' passed to React.createElement. Types that start with a
capital letter like <Foo /> compile to React.createElement(Foo) and
correspond to a component defined or imported in your JavaScript file.
Instead of <renderJob /> change to {renderJob}

In React ES6, why does the input field lose focus after typing a character?

In my component below, the input field loses focus after typing a character. While using Chrome's Inspector, it looks like the whole form is being re-rendered instead of just the value attribute of the input field when typing.
I get no errors from either eslint nor Chrome Inspector.
Submitting the form itself works as does the actual input field when it is located either in the render's return or while being imported as a separate component but not in how I have it coded below.
Why is this so?
Main Page Component
import React, { Component, PropTypes } from 'react';
import { connect } from 'react-redux';
import { bindActionCreators } from 'redux';
import * as actionPost from '../redux/action/actionPost';
import InputText from './form/InputText';
import InputSubmit from './form/InputSubmit';
class _PostSingle extends Component {
constructor(props, context) {
super(props, context);
this.state = {
post: {
title: '',
},
};
this.onChange = this.onChange.bind(this);
this.onSubmit = this.onSubmit.bind(this);
}
onChange(event) {
this.setState({
post: {
title: event.target.value,
},
});
}
onSubmit(event) {
event.preventDefault();
this.props.actions.postCreate(this.state.post);
this.setState({
post: {
title: '',
},
});
}
render() {
const onChange = this.onChange;
const onSubmit = this.onSubmit;
const valueTitle = this.state.post.title;
const FormPostSingle = () => (
<form onSubmit={onSubmit}>
<InputText name="title" label="Title" placeholder="Enter a title" onChange={onChange} value={valueTitle} />
<InputSubmit name="Save" />
</form>
);
return (
<main id="main" role="main">
<div className="container-fluid">
<FormPostSingle />
</div>
</main>
);
}
}
_PostSingle.propTypes = {
actions: PropTypes.objectOf(PropTypes.func).isRequired,
};
function mapStateToProps(state) {
return {
posts: state.posts,
};
}
function mapDispatchToProps(dispatch) {
return {
actions: bindActionCreators(actionPost, dispatch),
};
}
export default connect(mapStateToProps, mapDispatchToProps)(_PostSingle);
Text Input Component
import React, { PropTypes } from 'react';
const InputText = ({ name, label, placeholder, onChange, value, error }) => {
const fieldClass = 'form-control input-lg';
let wrapperClass = 'form-group';
if (error && error.length > 0) {
wrapperClass += ' has-error';
}
return (
<div className={wrapperClass}>
<label htmlFor={name} className="sr-only">{label}</label>
<input type="text" id={name} name={name} placeholder={placeholder} onChange={onChange} value={value} className={fieldClass} />
{error &&
<div className="alert alert-danger">{error}</div>
}
</div>
);
};
InputText.propTypes = {
name: PropTypes.string.isRequired,
label: PropTypes.string.isRequired,
placeholder: PropTypes.string.isRequired,
onChange: PropTypes.func.isRequired,
value: PropTypes.string,
error: PropTypes.string,
};
InputText.defaultProps = {
value: null,
error: null,
};
export default InputText;
Submit Button Component
import React, { PropTypes } from 'react';
const InputSubmit = ({ name }) => {
const fieldClass = 'btn btn-primary btn-lg';
return (
<input type="submit" value={name} className={fieldClass} />
);
};
InputSubmit.propTypes = {
name: PropTypes.string,
};
InputSubmit.defaultProps = {
name: 'Submit',
};
export default InputSubmit;
it is because you are rendering the form in a function inside render().
Every time your state/prop change, the function returns a new form. it caused you to lose focus.
Try putting what's inside the function into your render directly.
<main id="main" role="main">
<div className="container-fluid">
<FormPostSingle />
</div>
</main>
===>
<main id="main" role="main">
<div className="container-fluid">
<form onSubmit={onSubmit}>
<InputText name="title" label="Title" placeholder="Enter a title" onChange={onChange} value={valueTitle} />
<InputSubmit name="Save" />
</form>
</div>
</main>
This happened to me although I had keys set!
Here's why:
I was using a key from a text field. Inside the same block; I had an input field to update the value of the same text field. Now, since component keys are changing, react re-renders the UI. Hence loosing focus.
What to take from this:
Don't use keys which are constantly changing.
What's happening is this:
When your onChange event fires, the callback calls setState with the new title value, which gets passed to your text field as a prop. At that point, React renders a new component, which is why you lose focus.
My first suggestion would be to provide your components keys, particularly the form and the input itself. Keys allow React to retain the identity of components through renders.
Edit:
See this documentation on keys: https://reactjs.org/docs/lists-and-keys.html#keys
Example:
<TextField
key="password" // <= this is the solution to prevent re-render
label="eMail"
value={email}
variant="outlined"
onChange={(e) => setEmail(e.target.value)}
/>
Had the same issue and solved it in a quick & easy manner: just calling the component with {compName()} instead of <compName />
For instance, if we had:
const foo = ({param1}) => {
// do your stuff
return (
<input type='text' onChange={onChange} value={value} />
);
};
const main = () => (
<foo param1={true} />
);
Then, we just need to change the way we call the foo() component:
const main = () => (
{foo({param1: true})}
);
By adding
autoFocus="autoFocus"
in the input worked for me
<input
type="text"
autoFocus="autoFocus"
value = {searchString}
onChange = {handleChange}
/>
You have to use a unique key for the input component.
<input key="random1" type="text" name="displayName" />
The key="random1" cannot be randomly generated.
For example,
<div key={uuid()} className='scp-ren-row'>
uuid() will generate a new set of string for each rerender. This will cause the input to lose focus.
If the elements are generated within a .map() function, use the index to be part of the key.
{rens.map((ren,i)=>{
return(
<div key={`ren${i+1}`} className='scp-ren-row'>
{ren}{i}
</div>)
}
This will solve the issue.
I also had this problem, my problem was related to using another component to wrap the textarea.
// example with this problem
import React from 'react'
const InputMulti = (props) => {
const Label = ({ label, children }) => (
<div>
<label>{label}</label>
{ children }
</div>
)
return (
<Label label={props.label}>
<textarea
value={props.value}
onChange={e => props.onChange(e.target.value)}
/>
</Label>
)
}
export default InputMulti
when the state changed, react would render the InputMulti component which would redefine the Label component every time, meaning the output would be structurally the same, but because of JS, the function would be considered !=.
My solution was to move the Label component outside of the InputMulti component so that it would be static.
// fixed example
import React from 'react'
const Label = ({ label, children }) => (
<div>
<label>{label}</label>
{ children }
</div>
)
const InputMulti = (props) => {
return (
<Label label={props.label}>
<textarea
value={props.value}
onChange={e => props.onChange(e.target.value)}
/>
</Label>
)
}
export default InputMulti
I've noticed that people often place locally used components inside the component that wants to use it. Usually to take advantage of function scope and gain access to the parent component props.
const ParentComp = ({ children, scopedValue }) => {
const ScopedComp = () => (<div>{ scopedValue }</div>)
return <ScopedComp />
}
I never really thought of why that would be needed, since you could just prop-drill the props to the internal function and externalise it from the parent comp.
This problem is a perfect example of why you should always externalise your components from each other, even if they are used in one module. Plus you can always use smart folder structures to keep things close by.
src/
components/
ParentComp/
ParentComp.js
components/
ScopedComp.js
I had a similar issue when using styled-components inside a functional component. The custom input element was losing focus every time I typed a character.
After much searching and experimenting with the code, I found that the styled-components inside the functional component was making the input field re-render every time I typed a character as the template literal syntax made the form a function although it looks like an expression inside Devtools. The comment from #HenryMueller was instrumental in making me think in the right direction.
I moved the styled components outside my functional component, and everything now works fine.
import React, { useState } from "react";
import styled from "styled-components";
const StyledDiv = styled.div`
margin: 0 auto;
padding-left: 15px;
padding-right: 15px;
width: 100%;
`;
const StyledForm = styled.form`
margin: 20px 0 10px;
`;
const FormInput = styled.input`
outline: none;
border: 0;
padding: 0 0 15px 0;
width: 100%;
height: 50px;
font-family: inherit;
font-size: 1.5rem;
font-weight: 300;
color: #fff;
background: transparent;
-webkit-font-smoothing: antialiased;
`;
const MyForm = () => {
const [value, setValue] = useState<string>("");
const handleChange = (e: React.ChangeEvent<HTMLInputElement>) => {
setValue(e.target.value);
}
const handleSubmit = (e: React.FormEvent) => {
e.preventDefault();
if(value.trim() === '') {
return;
}
localStorage.setItem(new Date().getTime().toString(), JSON.stringify(value));
setValue('');
}
return (
<StyledDiv>
<StyledForm onSubmit={handleSubmit}>
<FormInput type="text"
id="inputText"
name="inputText"
placeholder="What Do You Want To Do Next?"
value={value}
onChange={handleChange}/>
</StyledForm>
</StyledDiv>
)
}
export default MyForm;
The best way to use styled-components in cases like this would be to save them in separate files and import them.
My issue was it was rerendering in a stateless component in the same file. So once I got rid of that unecessary stateless component and just put the code in directly, I didn't have unecessary rerenders
render(){
const NewSocialPost = () =>
<div className='new-post'>
<input
onChange={(e) => this.setState({ newSocialPost: e.target.value })}
value={this.state.newSocialPost}/>
<button onClick={() => this._handleNewSocialPost()}>Submit</button>
</div>
return (
<div id='social-post-page'>
<div className='post-column'>
<div className='posts'>
<Stuff />
</div>
<NewSocialPost />
</div>
<MoreStuff />
</div>
I'm new to React, and have been running into this issue.
Here's what I did to solve:
First move all of your components into your components folder and then import them where you want to use them
Make sure all of your form elements get a name and id property
Make sure all components as you walk up the tree get a unique key
Someone smarter than me can probably tell us why we can skip step one and keep everything inline so to speak, but this just helped me organize the code.
I think the real issue is React is rerendering everything (as already stated) and sometimes that rerender is happening on a parent component that doesn't have a key but needs one.
My problem was with ExpansionPanel components wrapping my custom components for form inputs. The panels needed key as well!
Hope this helps someone else out there, this was driving me crazy!
Basically create a ref and assign it to the input element
const inputRef = useRef(null); // Javascript
const inputRef = useRef<HTMLInputElement>(null); // Typescript
// In your Input Element use ref and add autofocus
<input ref={inputRef} autoFocus={inputRef.current === document.activeElement} {...restProps} />
This will keep the input element in focus when typing.
The problem is with dynamic render() caused by useState() function so you can do this for example.
in this code you should use onChange() to get just the new updated data and onMouseLeave() to handle the update but with condition that data is changed to get better performance
example child
export default function Child(){
const [dataC,setDataC]=useState()
return(<Grid>
<TextField
.
.
onChange={(r)=> setDataC(r.target.value) }
onMouseLeave={(e)=> {
if(dataC!=props.data) { // to avoid call handleupdate each time you leave the textfield
props.handlechange(e.target.value) // update partent.data
}
}
/>
</Grid>)
}
exmple parent
export default function Parent(){
const [data,setData]=useState()
return(
<Grid>
<Child handlechange={handlechanges} data={data}/>
</Grid>)
}
I was facing the same issue, as soon as I type any character, it was losing focus. adding autoFocus props helped me to resolve this issue.
TypeScript Code Snippet
Solution -
Add a unique key to the input element because it helps React to identify which item has changed(Reconciliation). Ensure that your key should not change, it has to be constant as well as unique.
If you are defining a styled component inside a react component. If your input element is inside that styled component then define that styled component outside the input's component. Otherwise, on each state change of the main component, it will re-render your styled component and input as well and it will lose focus.
import React, { useState } from "react";
import styled from "styled-components";
const Container = styled.div`
padding: 1rem 0.5rem;
border: 1px solid #000;
`;
function ExampleComponent() {
// Container styled component should not be inside this ExampleComponent
const [userName, setUserName] = useState("");
const handleInputChange = event => {
setUserName(event.target.value);
};
return (
<React.Fragment>
<Container> {/* Styled component */}
<input
key="user_name_key" // Unique and constant key
type="text"
value={userName}
onChange={handleInputChange}
/>
</Container>
</React.Fragment>
);
}
export default ExampleComponent;
In my case, I had this on a child,
//in fact is a constant
const RenderOnDelete=()=>(
<> .
.
<InputText/>
.
.
</>
)
//is a function that return a constant
const RenderOnRadioSelected=()=>{
switch (selectedRadio) {
case RADIO_VAL_EXIST:
return <RenderOnExist/>
case RADIO_VAL_NEW:
return <RenderOnNew/>
case RADIO_VAL_DELETE:
return <RenderOnDelete/>
default:
return <div>Error</div>
}
}
and this in the parent
return(
<>
.
<RenderOnRadioSelected/>
.
</>
)
Y solved it by not calling a component but a function() or a constant, depending on the case.
.
.
.
//in fact is a constant
const RenderOnDelete=(
<> .
.
<InputText/>
.
.
</>
)
//is a function that return a constant
const RenderOnRadioSelected=()=>{
switch (selectedRadio) {
case RADIO_VAL_EXIST:
return {RenderOnExist}
case RADIO_VAL_NEW:
return {RenderOnNew}
case RADIO_VAL_DELETE:
return {RenderOnDelete}//Calling the constant
default:
return <div>Error</div>
}
}
and this in the parent
return(
<>
.
{RenderOnRadioSelected()}//Calling the function but not as a component
.
</>
)
Adding yet another answer: This happened to me when returning a higher order component inside another component. Eg instead of:
/* A function that makes a higher order component */
const makeMyAwesomeHocComponent = <P, >(Component: React.FC<P>) => {
const AwesomeComponent: React.FC<P & AwesomeProp> = (props) => {
const { awesomeThing, ...passThroughProps } = props;
return (
<strong>Look at: {awesomeThing}!</strong>
<Component {...passThroughProps} />
);
}
return AwesomeComponent;
}
/* The form we want to render */
const MyForm: React.FC<{}> = (props) => {
const MyAwesomeComponent: React.FC<TextInputProps & AwesomeProp> =
makeMyAwesomeHocComponent(TextInput);
return <MyAwesomeComponent awesomeThing={"cat"} onChange={() => { /* whatever */ }} />
}
Move the call to create the higher order component out of the thing you're rendering.
const makeMyAwesomeHocComponent = <P, >(Component: React.FC<P>) => {
const AwesomeComponent: React.FC<P & AwesomeProp> = (props) => {
const { awesomeThing, ...passThroughProps } = props;
return (
<strong>Look at: {awesomeThing}!</strong>
<Component {...passThroughProps} />
);
}
return AwesomeComponent;
}
/* We moved this declaration */
const MyAwesomeComponent: React.FC<TextInputProps & AwesomeProp> =
makeMyAwesomeHocComponent(TextInput);
/* The form we want to render */
const MyForm: React.FC<{}> = (props) => {
return <MyAwesomeComponent awesomeThing={"cat"} onChange={() => { /* whatever */ }} />
}
Solution for this problem is to use useCallback It is used to memoize functions which means it caches the return value of a function given a set of input parameters.
const InputForm = useCallback(({ label, lablevalue, placeholder, type, value,setValue }) => {
return (
<input
key={label}
type={type}
value={value}
onChange={(e) => setIpValue(e.target.value)}
placeholder={placeholder}
/>
);
},[]);
Hope it will solve your problem
If you happen to be developing atomic components for your app's design system, you may run into this issue.
Consider the following Input component:
export const Input = forwardRef(function Input(
props: InputProps,
ref: ForwardedRef<HTMLInputElement>,
) {
const InputElement = () => (
<input ref={ref} {...props} />
);
if (props.icon) {
return (
<span className="relative">
<span className="absolute inset-y-0 left-0 flex items-center pl-2">
<label htmlFor={props.id} className="p-1 cursor-pointer">
{icon}
</label>
</span>
<InputElement />
</span>
);
} else {
return <InputElement />;
}
});
It might seem like a simple optimization at first to reuse your input element across both branches of your conditional render. However, anytime the parent of this component re-renders, this component re-renders, and when react sees <InputElement /> in the tree, it's going to render a new <input> element too, and thus, the existing one will lose focus.
Your options are
memoize the component using useMemo
duplicate some code and define the <input> element in both branches of the conditional render. in this case, it's okay since the <input> element is relatively simple. more complex components may need option 1
so your code then becomes:
export const Input = forwardRef(function Input(
props: InputProps,
ref: ForwardedRef<HTMLInputElement>,
) {
if (props.icon) {
return (
<span className="relative">
<span className="absolute inset-y-0 left-0 flex items-center pl-2">
<label htmlFor={props.id} className="p-1 cursor-pointer">
{icon}
</label>
</span>
<input ref={ref} {...props} />
</span>
);
} else {
return <input ref={ref} {...props} />;
}
});
I did the following steps:
Move dynamic component outside a function
Wrap with useMemo function
const getComponent = (step) =>
dynamic(() => import(`#/components/Forms/Register/Step-${step}`), {
ssr: false,
});
And call this function inside the component by wrapping useMemo:
const CurrentStep = useMemo(() => getComponent(currentStep), currentStep]);
I'm very late but I have been tracking down this issue for days now and finally fixed it. I hope it helps someone.
I'm using Material-ui's Dialog component, and I wanted the dialog to show when a menu item was clicked. Something like so:
import React, { useState } from "react";
import {
Menu,
MenuItem,
Dialog,
DialogContent,
TextField,
} from "#mui/material";
const MyMenu = () => {
const [open, setOpen] = useState(false);
return (
<Menu>
<MenuItem>option 1</MenuItem>
<MenuItem onClick={() => setOpen(!open)}>
option 2
<Dialog open={open}>
<DialogContent>
<TextField />
</DialogContent>
</Dialog>
</MenuItem>
</Menu>
);
};
I was having issues with the TextField losing focus, but only when hitting the a, s, d, c and v keys. If I hit any one of those keys, it would not type anything in the textfield and just lose focus. My assumption upon fixing the issue was that some of the menu options contained those characters, and it would try to switch focus to one of those options.
The solution I found was to move the dialog outside of the Menu component:
const MyMenu = () => {
const [open, setOpen] = useState(false);
return (
<>
<Menu>
<MenuItem>option 1</MenuItem>
<MenuItem onClick={() => setOpen(!open)}>
option 2
</MenuItem>
</Menu>
<Dialog open={open}>
<DialogContent>
<TextField />
</DialogContent>
</Dialog>
</>
);
};
I am unable to find anyone with my specific issue online, and this was the post that came up at the top in my searches so I wanted to leave this here. Cheers
I am not authorised to comment then it must be an answer. I had similar issue and Answer from Alex Yan was corect.
Namely I had that function
const DisplaySearchArea =()=>{return (arrayOfSearchFieldNames.map((element, index)=>{return(<div key ={index} className = {inputFieldStyle}><input placeholder= {arrayOfPlaceholders[index]} type="text" className='border-0'
value={this.state[element]}
onChange={e => {this.setState({ [element]: e.target.value }); console.log(e.target)}}
onMouseEnter={e=>e.target.focus()}/></div>)}))}
that behaves OK with FF and not with Chrome when rendered as <DisplaySearchArea />
When render as {...} it's OK with both. That is not so 'beaty' looking code but working, I have already been told to have tendency to overuse lambdas.
Thanks, Alex. This way I solved my issue:
constructor(props, context) {
...
this.FormPostSingle = this.FormPostSingle.bind(this);
}
FormPostSingle() {
const onChange = this.onChange;
const onSubmit = this.onSubmit;
const valueTitle = this.state.post.title;
return (
<form onSubmit={onSubmit}>
<InputText name="title" label="Title" placeholder="Enter a title" onChange={onChange} value={valueTitle} />
<InputSubmit name="Save" />
</form> );
}
render() {
let FormPostSingle = this.FormPostSingle
return...
}
set the correct id, make sure no other component has same id, set it unique, and it should not change on state update, most common mistake is updating the id with changed value on state update
I had this issue, it was being cause by react-bootstrap/Container, once I got rid of it, included a unique key for every form element, everything worked fine.
For the ones on React Native facing the issue where the text input goes out of focus after typing in single character.
try to pass your onChangeText to your TextInput component.
eg:
const [value, setValue] = useState("")
const onChangeText = (text) => {
setValue(text)
}
return <TextInput value={value} onChangeText={onChangeText} />
This is a great question, and I had the same problem which was 3 parts.
RandomGenerated keys.
Wrong event type.
wrong react JSX attribute.
Keys: when you use random keys each rerender causes react to lose focus (key={Math.random()*36.4621596072}).
EventTypes: onChange cause a rerender with each key stroke, but this can also cause problems. onBlur is better because it updates after you click outside the input. An input, unless you want to "bind" it to something on the screen (visual builders), should use the onBlur event.
Attributes: JSX is not HTML and has it's own attributes (className,...).
Instead of using value, it is better to use defaultValue={foo} in an input.
once I changes these 3 things it worked great. Example below.
Parent:
const [near, setNear] = useState( "" );
const [location, setLocation] = useState( "" );
<ExperienceFormWhere
slug={slug}
questionWhere={question_where}
setLocation={handleChangeSetLocation}
locationState={location}
setNear={setNear}
nearState={near}
key={36.4621596072}/>
Child:
<input
defaultValue={locationState}
className={slug+"_question_where_select search_a_location"}
onBlur={event => setLocation(event.target.value)}/>
I did it with a useRef on input and useEffect
For me this was happening inside Material UI Tabs. I had a search input filter which filtered the table records below it. The search input and table were inside the Tab and whenever a character was typed the input would lose focus (for the obvious reason of re render, the whole stuff inside a tab).
I used the useRef hook for input field ref and then inside my useEffect I triggered the input's focuswhenever the datalist changed. See the code below
const searchInput = useRef();
useEffect(() => {
searchInput.current.focus();
}, [successfulorderReport]);
If working with multiple fields – and they have to be added and removed dynamically for whatever reason – you can use autofocus. You have to keep track of the focus yourself, though. More or less like this:
focusedElement = document.activeElement.id;
[…]
const id = 'dynamicField123'; // dynamically created.
<Input id={id} key={id} {...(focusedElement === id ? { autoFocus: true } : {})} />
This issue got me for a second. Since I was using Material UI, I tried to customize one of the wrapper components of my form using the styled() API from material UI. The issue was caused due to defining the DOM customization function inside my render function body. When I removed it from the function body, it worked like a charm. So my inspection is, whenever I updated the state, it obviously tried to refresh the DOM tree and redeclare the styled() function which is inside the render body, which gave us a whole new reference to the DOM element for that wrapper, resulting in a loss of focus on that element. This is just my speculation, please enlighten me if I am wrong.
So removing the styled() implementation away from the render function body solved the issue for me.
This is silly, but... are you (reader, not OP) setting disabled={true} ever?
This is a silly contribution, but I had a problem very much like the one this page is talking about. I had a <textarea> element inside a component that would lose focus when a debounce function concluded.
Well, I realized I was on the wrong track. I was setting the <textarea> to disabled={true} whenever an auto-save function was firing because I didn't want to let the user edit the input while their work was being saved.
When a <textarea> is set to be disabled it will lose focus no matter what trick you try shared here.
I realized there was zero harm in letting the user continue to edit their input while the save was occurring, so I removed it.
Just in case anyone else is doing this same thing, well, that might be your problem. 😅 Even a senior engineer with 5 years of React experience can do things that dumb.

Range bar in redux form

i have a range bar which i create from react-slider. I want to use it in a redux-form. My problem is that the values are not returning. To be more specific when i sumbit my form the other fields return values while this range bar returns undefined. How do i have to use the Range in a redux-form?? My code is
<FormGroup className="col-sm-3 ">
<Label for="value-slider">VALUE</Label>{' '}
<Field
id="value-slider"
name="value-slider"
component={Range}
/>
</FormGroup>
You cannot pass any random component to component prop. It must implement interface of redux-form (see usage), what Range does not. In short, passed element must at least trigger event with input.onChange and display value from input.value prop:
const MyRange = props => (
<Range value={props.input.value} onChange={props.input.onChange} />
)
And then use it:
<Field
id="value-slider"
name="value-slider"
component={MyRange}
/>
I've run into this issue just now, thanks to maddox2 for the answer which set me along the right lines, however, as one user pointed out in the comments above, the solution above will give TypeError: value.map is not a function.
To fix this, you need to explicitly set the type of the field in initialValues, when you use reduxForm()to create the form. Example code is below.
Note how additional props used by Range are also passed to ReduxRange in the props prop, and that these are then passed down to the Range in the wrapping component.
import React from 'react';
import { Field, reduxForm } from 'redux-form'
import Range from 'rc-slider/lib/Range';
import 'rc-slider/assets/index.css';
// initial wrapper - note alterations
const ReduxRange = props => {
const { input: { value, onChange } } = props
return (
<Range
value={props.input.value}
onChange={props.input.onChange}
{...props}
/>
)
}
// the form
export const SomeReduxForm = props => {
const { handleSubmit } = props;
// these props will get passed to the Range
const rangeProps = {
defaultValue:[2020, 2040],
marks:{
2020: '2020',
2030: '2030',
2040: '2040',
2050: '2050',
2060: '2060',
2070: '2070',
2080: '2080',
},
pushable:true,
allowCross:false,
min:2018,
max:2080,
step:1,
}
return (
<section className="box box-default">
<form>
<div className="box-header">Year Range</div>
<div className="box-body">
<Field
name="yearRange"
component={ReduxRange}
props={rangeProps}
/>
</div>
</form>
</section>
)
}
export default reduxForm({
form: 'someReduxForm',
initialValues: {
yearRange: [2020, 2040]
}
})(SomeReduxForm)

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