How to Manipulate Dropdown placeholder, onFocus? - reactjs

Question

Am new to ReactJS. I need to make the "placeholder" which is set to "State" initially to Empty/Null when onClicked or onFocus and then when it's not focused on, it goes back to "State" again. Can someone help me with this, am very new to react so any help will be appreciated.
import React from "react";
import { render } from "react-dom";
import { Container, Button, Modal, Dropdown } from "semantic-ui-react";
const stateOptions = [
{ key: "AL", value: "AL", text: "Alabama" },
{ key: "NY", value: "NY", text: "New York" }
];
const App = () => (
<Dropdown
placeholder="State"
fluid
multiple
search
selection
options={stateOptions}
/>
);
render(<App />, document.getElementById("root"));

Answer 1

From React's perspective, placeholder is a state that needs to be changed according to user's actions (onClick, onBlur)
So create a state to hold placeholder value that need to change.
There are two ways (since v16.8.0 with the introduction of React Hooks).
Using Class Component
class DropDown extends React.Component {
defaultPlaceholderState = "State";
state = { placeholder: this.defaultPlaceholderState };
clearPlaceholder = () => this.setState({ placeholder: "" });
resetPlaceholder = () =>
this.setState({ placeholder: this.defaultPlaceholderState });
render() {
return (
<Dropdown
onClick={this.clearPlaceholder}
onFocus={this.clearPlaceholder}
onBlur={this.resetPlaceholder}
placeholder={this.state.placeholder}
fluid
multiple
search
selection
options={stateOptions}
/>
);
}
}
In the code above, placeholder declared as a state with default value set to this.defaultPlaceholderState.
When a user clicks on the dropdown, onClick clears the placeholder value by setting it to an empty string. Same for onFocus when the Dropdown is on focus.
When a user clicks outside (onBlur), resetPlaceHolder sets the placeholder value to the default this.defaultPlaceholderState.
Using Function Component with useState hook
React v16.8.0 introduces Hooks, which enables Function Components (not a Functional Component, as it refers to Functional Programming) to hold states.
You can use React.useState hook to hold placeholder value.
const DropDownUsingHook = () => {
const defaultPlaceholderState = "State";
const [placeholder, setPlaceholder] = React.useState(defaultPlaceholderState);
const clearPlaceholder = () => setPlaceholder("");
const resetPlaceholder = () => setPlaceholder(defaultPlaceholderState);
return (
<Dropdown
onClick={clearPlaceholder}
onFocus={clearPlaceholder}
onBlur={resetPlaceholder}
placeholder={placeholder}
fluid
multiple
search
selection
options={stateOptions}
/>
);
};
⚠ Note: Unlike the Class version, clearPlaceholder, resetPlaceholder methods and placeholder state don't use this. prefix.
The implementation is similar but you use useState hook to declare the state and the setter (setPlaceholder).
Refer to the Hooks documentation, Using State Hook for more info.
You can play around with the working code on CodeSandbox.