React retrieve checked value in checkbox - reactjs

I am trying to retrieve the checked values of the checkboxes and save them into array.
I tried :
arr.push(setNewItem(checked))
arr.push(e.target.value.checked)
arr.push(items.checked)
But these return type error or undefined values.
const [checkedItems, setCheckedItems] = useState([]);
const handleChange = (e) => {
if (e.target.checked) {
var arr = [...checkedItems];
//arr.push(setNewItem(e.target.value.checked));
setCheckedItems(arr);
console.log(arr);
} else {
checkedItems = "";
}
setIsChecked((current) => !current);
};
return (
<div className="App">
<StyleForm>
<StyleInput
type="text"
placeholder="Add"
value={newItem}
onChange={(e) => setNewItem(e.target.value)}
onKeyPress={handleOnKeyPress}
/>
<ButtonAddStyle onClick={() => addItem()}>add</ButtonAddStyle>
<StyleUl>
{items.map((item) => {
return (
<StyleLi key={item.id}>
<StyleCheckBox
type="checkbox"
value={isChecked}
onChange={handleChange}
/>
{item.value}
{""}
<ButtonDelStyle onClick={() => deleteItem(item.id)}>
X
</ButtonDelStyle>
</StyleLi>
);
})}
</StyleUl>
</StyleForm>
</div>
);

arr.push(e.target.checked);
Is the way to go and get rif of :
else {
checkedItems = "";
}
you cannot update a hook this way you will get an error when you try to unchek an input:
Uncaught TypeError : Assignment to constant variable
Now let's see what you are trying to do you are storing e.target.checked each time an input is cheked so checkedItems will look something like this :
[true, true, true, true, true, true, true, true]
why do you need this ? better is to store the ids of checked items :
const handleChange = (isChecked, id) => {
var arr = [...checkedItems];
if (isChecked) {
arr.push(id);
setCheckedItems(arr);
} else {
setCheckedItems(checkedItems.filter((storedId) => storedId !== id)); // delete the id from checkedItems if the corresponding input is unckecked
}
};
and from jsx :
<StyleCheckBox
type="checkbox"
value={item.id}
onChange={(e) => {
handleChange(e.target.checked, item.id);
}}
/>;
Now look at this :
<StyleCheckBox
value={isChecked} // this line
>
you are mapping through items creating multiple checkBoxes but all of them share the same value. and the value attribute of an input of type checkbox is not what you think it is, learn more here. so you can use value={item.id} to have an unique value for each input and get rid of isChecked useState hook you really don't need it

this could solve your problem.
const [checkedItems, setCheckedItems] = useState([]);
const handleChange = (e) => {
setCheckedItems( prev => [...prev, e.target.checked]);
setIsChecked((current) => !current);
};

Related

how to update input defaultvalue using useRef (after the initial render?)

const Component = ()=>{
const [list, setList] = useState(getLocalStorage());
const [isEditing, setIsEditing] = useState(false);
const [itemToEdit, setItemToEdit] = useState();
const refContainer = useRef(null);
const putLocalStorage = () => {
localStorage.setItem("list", JSON.stringify(list));
};
const editItem = (id) => {
refContainer.current.focus();
setItemToEdit(() => {
return list.find((item) => item.id === id);
});
setIsEditing(true);
};
const handleSubmit = (e)=>{
e.preventDefault();
let nameValue = refContainer.current.value;
if (isEditing){
setList(list.map((item)=>{
if (item.id === itemToEdit.id){
return {...item, name: nameValue};
}
else {
return item;
}
);
}
else {
let newItem = {
id: new Date().getItem().toString(),
name: nameValue,
}
setList([...list, newItem])
}
nameValue="";
setIsEditing(false);
}
useEffect(() => {
putLocalStorage();
}, [list]);
return (
<div>
<form onSubmit={handleSubmit}>
<input type="text" ref={refContainer} defaultValue={isEditing ? itemToEdit.name : ""}/>
<button type="submit">submit</button>
</form>
<div>
{list.map((item) => {
const { id, name } = item;
return (
<div>
<h2>{name}</h2>
<button onClick={() => editItem(id)}>edit</button>
<button onClick={() => deleteItem(id)}>
delete
</button>
</div>
);
})}
</div>
</div>
)
}
So this part:
<input type="text" ref={refContainer} defaultValue={isEditing ? itemToEdit.name : ""} />
I want to show to users what they are editing by displaying the itemToEdit on the input.
It works on the first time when the user clicks edit button
But after that, the defaultValue does not change to itemToEdit
Do you guys have any idea for the solution?
(i could use controlled input instead, but i want to try it with useRef only)
Otherwise, placeholder will be the only solution...
The defaultValue property only works for inicial rendering, that is the reason that your desired behavior works one time and then stops. See a similar question here: React input defaultValue doesn't update with state
One possible solution still using refs is to set the itemToEdit name directly into the input value using ref.current.value.
const editItem = (id) => {
refContainer.current.focus();
setItemToEdit(() => {
const item = list.find((item) => item.id === id);
refContainer.current.value = item.name;
return item;
});
setIsEditing(true);
};

How to get a value from onChange in react.js?

I'm trying to get value from onChange using setState but for some reason when I write text on input I get an error like Axis.map is not a function
Also,I'd like to delete Axisdata singly from the last one using splice or pop but whenever I click the delete button the Axis data disappeared except the first one.
Set Elements
const SetElements = ({
...
}) => {
const [Axis, setAxis] = useState([]);
const AxisHandler = e => {
setAxis([
...Axis,
{
label: "",
data: "",
backgroundColor: "",
},
]);
};
const deleteAxis = () => {
setAxis(Axis.splice(-1, 1));
};
return (
<>
<button onClick={AxisHandler}>add Line</button>
{Axis.length !== 1 && (
<button onClick={deleteAxis}>delete Line</button>
)}
{Axis.map((element, index) => (
<>
<AppendingAxis
Axis={Axis}
setAxis={setAxis}
element={element}
index={index}
/>
</>
))}
</>
)
AppendingAxis
const AppendingAxis = ({
index,
setAxis,
Axis,
}) => {
console.log(Axis);
return (
<AxisSetting>
<h4>{index + 2}Y Axis setting</h4>
<span>
<input
placeholder={index + 2 + "setting"}
type="textarea"
onChange={e => setAxis((Axis[index].label = e.target.value))}
/>
</span>
The issue is state mutation in the AppendingAxis component.
onChange={e => setAxis((Axis[index].label = e.target.value))}
You should shallow copy state, and nested state, then update specific properties.
onChange={e => setAxis(Axis => Axis.map((el, i) => i === index
? {
...el,
label: e.target.value
}
: el,
)}
I'm not a fan of passing the state updater function on to children as this make it the child component's responsibility to maintain your state invariant. I suggest moving this logic into the parent component so it can maintain control over how state is updated.
SetElements parent
const changeHandler = index => e => {
const { value } = e.target;
setAxis(Axis => Axis.map((el, i) => i === index
? {
...el,
label: value
}
: el,
);
};
...
<AppendingAxis
Axis={Axis}
onChange={changeHandler(index)}
/>
AppendingAxis child
const AppendingAxis = ({ Axis, onChange }) => {
console.log(Axis);
return (
<AxisSetting>
<h4>{index + 2}Y Axis setting</h4>
<span>
<input
placeholder={index + 2 + "setting"}
type="textarea"
onChange={onChange}
/>
</span>
And for completeness' sake, your delete handler looks to also have a mutation issue.
const deleteAxis = () => {
setAxis(Axis.splice(-1, 1));
};
.splice mutates the array in-place and returns an array containing the deleted elements. This is quite the opposite of what you want I think. Generally you can use .filter or .slice to generate new arrays and not mutate the existing one.
const deleteAxis = () => {
setAxis(Axis => Axis.slice(0, -1)); // start at 0, end at second to last
};
This is happening because of this line:
onChange={e => setAxis((Axis[index].label = e.target.value))}
Create a function:
const handleAxisChange = (e, index) => {
Axis[index].label = e.target.value;
setAxis(new Array(...Axis));
}
And then change set the onChange like this:
onChange={e => handleAxisChange(e, index)}
Your problem is because of you don't mutate state correctly. You should make a shallow copy of the state. You can change AppendingAxis to this code:
const AppendingAxis = ({
index,
setAxis,
Axis,
}) => {
console.log(Axis);
const onChange = (e,index)=>{
let copy = [...Axis];
copy[index].label = e.target.value;
setAxis(copy);
}
return (
<AxisSetting>
<h4>{index + 2}Y Axis setting</h4>
<span>
<input
placeholder={index + 2 + "setting"}
type="textarea"
onChange={e => onChange(e,index))}
/>
</span>

handling multiple checkboxs and push or filter values based on selection

how to handle checkbox is selected or not and push the object if selected and remove if unselected?
this is the initial arr set to state
let arr=[{lable:lable1,value:value1}
{lable:lable2,value:value2}
{lable:lable3,value:value3}
]
handle function triggered on selecting checkbox
function handleChange(item) {
let temp = [...arr];
if (temp.includes(item.value)) {
temp = temp.filter((value) => value != item.value);
} else {
temp.push(item.value);
}
setState(temp);
}
multiple checkbox iterated based on array
{arr.map((item, i) => {
return (
<label className="check-wrap">
<input
className="check-field"
checked={ ? } // how to handle checkbox is selected or not
name={item.lable}
onChange={() => handleChange(item)}
type="checkbox"
/>
<span className="check-label">{item.value}</span>
</label>
</div>
))}
issue in codesandbox
You should use prevState instead of referencing the state value directly.
// ... rest of the onChange function
this.setState(prevState => ({
arr: prevState.arr.includes(temp)
? prevState.arr.filter(value => value !== item.value)
: [...prevState.arr, temp]
}))
You can read up on setState operations in reactjs here
Hooks works on the same principle:
const [arr, setArr] = useState([])
// ...later
setArr(prevArr => prevArr.includes(temp)
? prevArr.fitler(value => value !== item.value)
: [...prevArr, temp]
)

Cannot remove inputs array with filter

I am trying to remove an input field with filter function but it's not working.
In the following code add operation works fine but remove operation is not working properly ,it is not removing the corresponding element.Another problem the values on the inputs fields not present when the component re-renders.so experts guide me how i can achieve removing the corresponding row when the remove button is clicked and the input values should not be reset when the component re-renders
So when I refresh the page and click to remove an input it will clear all other input data. How can I fix this problem ?
Update adding full component in question:
const Agreement = (props) => {
const { agreement, editable, teamData, teamId, fetchTeamData } = props;
const [editing, setEditing] = useState(false);
const [title, setTitle] = useState("");
const [showErrors, setShowErrors] = useState(false);
const [errorsArr, setErrorsArr] = useState();
const initialFormState = {
rule_0: teamData.rules.rule_0,
rule_1: teamData.rules.rule_1,
rule_2: teamData.rules.rule_2,
rule_3: teamData.rules.rule_3,
creator: teamData.User.public_user_id,
};
const [updateTeamData, setUpdateTeamData] = useState(initialFormState);
const [inputs, setInputs] = useState(
teamData.rules.map((el) => ({
...el,
guid: uuidV4(),
}))
);
const handleChange = (event) => {
const { name, value } = event.target;
// Update state
setUpdateTeamData((prevState) => ({
...prevState,
[name]: value,
}));
};
// Add more input
const addInputs = () => {
setInputs([...inputs, { name: `rule_${inputs.length + 1}` }]);
};
// handle click event of the Remove button
const removeInputs = (index) => {
const newList = inputs.filter((item, i) => index !== i); // <-- compare for matching index
setInputs(newList);
};
const clearInput = (dataName) => {
setUpdateTeamData((prevState) => {
delete prevState[dataName];
return {
...prevState,
};
});
};
const handleSubmit = async (event) => {
event.preventDefault();
setEditing(false);
// Send update request
const res = await axios.put(`/api/v1/teams/team/${teamId}`, updateTeamData);
// If no validation errors were found
// Validation errors don't throw errors, it returns an array to display.
if (res.data.validationErrors === undefined) {
// Clear any errors
setErrorsArr([]);
// Hide the errors component
setShowErrors(false);
// Call update profiles on parent
fetchTeamData();
} else {
// Set errors
setErrorsArr(res.data.validationErrors.errors);
// Show the errors component
setShowErrors(true);
}
};
const handleCancel = () => {
setEditing(false);
};
useEffect(() => {
if (agreement === "default") {
setTitle(defaultTitle);
// setInputs(teamData.rules);
} else {
setTitle(agreement.title ?? "");
}
}, [agreement, teamData]);
// console.log("teamData.rules", teamData);
console.log("inputs", inputs);
return (
<div className="team-agreement-container">
{!editing && (
<>
<h4 className="team-agreement-rules-title">{title}</h4>
{editable && (
<div className="team-agreement-rules">
<EditOutlined
className="team-agreement-rules-edit-icon"
onClick={() => setEditing(true)}
/>
</div>
)}
{teamData.rules.map((rule, index) => (
<div className="team-agreement-rule-item" key={`rule-${index}`}>
{rule ? (
<div>
<h4 className="team-agreement-rule-item-title">
{`Rule #${index + 1}`}
</h4>
<p className="team-agreement-rule-item-description">
- {rule}
</p>
</div>
) : (
""
)}
</div>
))}
</>
)}
{/* Edit rules form */}
{editing && (
<div className="team-agreement-form">
{showErrors && <ModalErrorHandler errorsArr={errorsArr} />}
<h1>Rules</h1>
{inputs.map((data, idx) => {
return (
<div className="agreement-form-grid" key={data.guid}>
<button
type="button"
className="agreement-remove-button"
onClick={() => {
removeInputs(idx);
clearInput(`rule_${idx}`);
}}
>
<Remove />
</button>
<input
name={`rule_${idx}`}
onChange={handleChange}
value={teamData.rules[idx]}
/>
</div>
);
})}
{inputs.length < 4 && (
<div className="team-agreement-add-rule">
<button type="submit" onClick={addInputs}>
<Add />
</button>
</div>
)}
<div className="div-button">
<button className="save-button" onClick={handleSubmit}>
Save
</button>
<button className="cancel-button" onClick={handleCancel}>
Cancel
</button>
</div>
</div>
)}
</div>
);
};
export default Agreement;
When i do console.log(inputs) this is the data that I got:
0: 0: "t" 1: "e" 2: "s" guid: "e18595a5-e30b-4b71-8fc2-0ad9c0e140b2"
proto: Object 1: 0: "d" 1: "a" 2: "s" 3: "d" 4: "a" 5: "s" guid: "537ca359-511b-4bc6-9583-553ea6ebf544" ...
Issue
The issue here is that you are using the array index as the React key. When you mutate the underlying data and reorder or add/remove elements in the middle of the array then the elements shift around but the React key previously used doesn't move with the elements.
When you remove an element then all posterior elements shift forward and the index, as key, remains the same so React bails on rerendering the elements. The array will be one element shorter in length and so you'll see the last item removed instead of the one you actually removed.
Solution
Use a React key that is intrinsic to the elements being mapped, unique properties like guids, ids, name, etc... any property of the element that guarantees sufficient uniqueness among the dataset (i.e. the siblings).
const [inputs, setInputs] = useState(teamData.rules);
const removeInputs = (index) => {
// compare for matching index
setInputs(inputs => inputs.filter((item, i) => index !== i));
};
{inputs.map((data, idx) => {
return (
<div className="agreement-form-grid" key={data.id}> // <-- use a unique property
<button
type="button"
className="agreement-remove-button"
onClick={() => {
removeInputs(idx);
clearInput(`rule_${idx}`);
}}
>
<Remove />
</button>
<input
name={`rule_${idx}`}
onChange={handleChange}
value={teamData.rules[idx]}
/>
</div>
);
})}
If your teamData.rules initial state value doesn't have any unique properties to use then you can map this to a new array and add a sufficient id property.
const [inputs, setInputs] = useState(teamData.rules.map(el => ({
...el,
guid: generateId()***,
})));
*** this is a function you need to define yourself, or import from a module like uuid***
import { v4 as uuidV4 } from 'uuid';
...
const [inputs, setInputs] = useState(teamData.rules.map(el => ({
...el,
guid: uuidV4(),
})));
// Add more input
const addInputs = () => {
setInputs(inputs => [
...inputs,
{
name: `rule_${inputs.length + 1}`,
guid: uuidV4();
},
]);
};
Then when mapping use the guid property.
<div className="agreement-form-grid" key={data.guid}>
The issue is because you are trying to compare index with array item in filter method. You should use the second argument in filter which denotes the array index of the current iterating item
const removeInputs = (index) => {
const newList = inputs.filter((item,i) => index !== i);
setInputs(newList);
};
That's your solution, you are trying with item but you are comparing it with index that's wrong. You should do it like this,
const newList = inputs.filter((item, key) => index !== key);

How to set the first value in a select dropdown to as a default react

I have a react program that displays a table based on values of a dropdown. I want the program to display the table by default based on the first value in the dropdown.
The first value in the dropdown is very different from the value made as default, and the dropdown values are always changing. So the data can be misleading when it loads for the first time.
here is a snippet of my code with a little description within. Thanks.
const CompletenessApp = () => {
const [completeness, setcompleteness] = useState([]);
const [loading, setloading] = useState(false);
const [valueSelected, setValueSelected] = useState({value:'all'});
const [periodSelected, setPeriodSelected] = useState({value:'20200702'}); // the default value that is used to filter the data.
const valid = [
{id:"all", variable:"all"},{id:"true", variable:"true"}, {id:"false", variable:"false"}, {id:"null", variable:"null"},
];
useEffect(() => {
const fetchData = async () => {
try{
const res = await axios.get('http://localhost:8000/api/completeness/');
setcompleteness(res.data);
setloading(true);
} catch (e) {
console.log(e)
}
}
fetchData();
}, []);
// when the page loads for the first time it filters the data based on the period value set in the state. I want the data to be filtered based on the first value in the dropdown instead, the first value in the dropdown is different from the default value set.
const handlePeriodChange = e => {
setPeriodSelected({value : e.target.value})
}
const handleValueChange = e => {
let boolvalue = Boolean
e.target.value === 'true'? boolvalue = true:
e.target.value === 'false'? boolvalue = false:
e.target.value === 'all'? boolvalue = 'all':
boolvalue=null
setValueSelected({value : boolvalue})
}
//filtered data to be displayed
const filteredCompleteness = completeness.filter(
completedata=> (completedata.period === periodSelected.value)
&&(valueSelected.value !== 'all'?completedata.complete === valueSelected.value:{}))
return(
<div>
<div className="selection-row">
<div className="stats-columns">
<div className="stats-label">Period</div>
//the relevant dropdown is here
<select onChange={e => handlePeriodChange(e)}>
{Array.from(new Set(completeness.map(obj => obj.period)))
.sort().reverse()
.map(period => {
return <option value={period}>{period}</option>
})}
</select>
</div>
<div className="stats-columns">
<div className="stats-label">Value</div>
<select onChange={e => handleValueChange(e)}>
{valid.map((obj) => {
return <option value={obj.id}>{obj.variable}</option>
})
}
</select>
</div>
</div>
<hr></hr>
<div className="results-table">
//table is displayed here
</div>
</div>
);
}
export default CompletenessApp;
// above return
const options = Array.from(new Set(completeness.map((obj) => obj.period)))
.sort()
.reverse()
.map((period) => {
return {
value: period,
label: period,
};
});
// in jsx
<select defaultValue={options[0].value} onChange={e => handlePeriodChange(e)}>
{
options.map((obj) => {
return <option value={obj.value}>{obj.label}</option>;
})
}
</select>
Try this and let me know.

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