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I have a component, let's say it contains a form. The form has child components which are essentially UI widgets for outputting text inputs and select menus.
The select menu components are a bit fancy and do some state maintaining using the onChange event.
My question is; how do I hook into the onChange event for a select menu from the parent (form) component? I can't pass onChange through props as I already have onChange specified inside the select component and I don't want to override it.
Example:
var Form = React.createClass({
handleSelectChange: function(){
// Do something when <Select /> changes
},
render: function () {
var selectMenuOptions = [
{label: 'Choose...', value: ''},
{label: 'First option', value: 'one'},
{label: 'Second option', value: 'two'}
];
return (
<form>
<Select name="selectMenu" id="selectMenu" options={selectMenuOptions} />
</form>
);
}
});
var Select = React.createClass({
getDefaultProps: function() {
return {
options: [],
className: "select"
};
},
getInitialState: function () {
return {
buttonText: 'Loading...',
defaultValue: null
};
},
handleChange: function (e) {
// Update buttonText state
},
render: function () {
return (
<div className={this.props.className}>
<div className="select__button">{this.state.buttonText}</div>
<select className="select__selector"
ref="select"
onChange={this.handleChange}>
{this.props.options.map(function(option, i){
return (<Option option={option} key={i} />);
})}
</select>
</div>
);
}
});
892
To pass an onChange event handler to a child component in React: Define the event handler function in the parent component. Pass it as a prop to the child component, e.g. <Child handleChange={handleChange} /> . Set it to the onChange prop on the input field in the child.
To use the addEventListener method in function components in React: Set the ref prop on the element. Use the current property on the ref to get access to the element. Add the event listener in the useEffect hook.
In the parent component, create a callback function. This callback function will retrieve the data from the child component. Pass the callback function to the child as a props from the parent component. The child component calls the parent callback function using props and passes the data to the parent component.
Parent Child Component Communication in React.js. Step 1: Create a new folder on the drive and open it in in VSCode. Name, the folder as react_reading_all_inputs. Step 2: Open Node.js command prompt and navigate to the folder created in Step 1. Since we need package.json for defining application dependencies, run the following command from the ...
So here is a clear explanation of how to pass data or events from child component to parent component in different ways. First Method — Functional child component to Parent functional component Create a child component and put the below code inside that component.
When using React you should generally not need to call addEventListener to add listeners to a DOM element after it is created. Instead, just provide a listener when the element is initially rendered. When you define a component using an ES6 class, a common pattern is for an event handler to be a method on the class.
Handling Events. Handling events with React elements is very similar to handling events on DOM elements. There are some syntactic differences: React events are named using camelCase, rather than lowercase. With JSX you pass a function as the event handler, rather than a string.
Using <Select onChange={...} /> won't override the <select onChange={...} /> inside Select's render method. The <Select/> component and the <select/> component it renders have completely different sets of props.
The simplest way to do what you want, I think, is to have your Select's handleChange method call this.props.onChange. You can just pass it the same e argument handleChange receives:
var Form = React.createClass({
handleSelectChange: function(){
// Do something when <Select /> changes
},
render: function () {
// ...
return (
<form>
<Select name="selectMenu"
id="selectMenu"
options={selectMenuOptions}
onChange={this.handleSelectChange} />
</form>
);
}
});
var Select = React.createClass({
// ...
handleChange: function (e) {
if (this.props.onChange) {
this.props.onChange(e);
}
// Update buttonText state
},
render: function () {
return (
<div className={this.props.className}>
<div className="select__button">{this.state.buttonText}</div>
<select className="select__selector"
ref="select"
onChange={this.handleChange}>
{this.props.options.map(function(option, i){
return (<Option option={option} key={i} />);
})}
</select>
</div>
);
}
});
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