The answer here depends on whether or not your inputs are controlled or uncontrolled. If you are unsure or need more info on this, check out what the official docs say about controlled components and uncontrolled components. Thanks @Dan-Esparza for providing the links.
Also, please note that using string literals in ref is deprecated. Use the standard callback method instead.
Clearing a form with uncontrolled fields
You can clear the entire form rather than each form field individually.
cancelCourse = () => {
document.getElementById("create-course-form").reset();
}
render() {
return (
<form id="create-course-form">
<input />
<input />
...
<input />
</form>
);
}
If your form didn’t have an id attribute you could use a ref as well:
cancelCourse = () => {
this.myFormRef.reset();
}
render() {
return (
<form ref={(el) => this.myFormRef = el;}>
<input />
<input />
...
<input />
</form>
);
}
Clearing a form with controlled fields
If you are using controlled form fields, you may have to explicitly reset each component inside your form, depending on how your values are stored in the state.
If they are declared individually, you need to reset each one explicitly:
cancelCourse = () => {
this.setState({
inputVal_1: "",
inputVal_2: "",
...
inputVal_n: "",
});
}
render() {
return (
<input value={this.state.inputVal_1} onChange={this.handleInput1Change}>
<input value={this.state.inputVal_2} onChange={this.handleInput2Change}>
...
<input value={this.state.inputVal_n} onChange={this.handleInputnChange}>
);
}
Demo below:
class MyApp extends React.Component {
constructor() {
super();
this.state = {
inputVal_1: "",
inputVal_2: "",
inputVal_3: "",
inputVal_4: "",
inputVal_5: "",
inputVal_6: "",
inputVal_7: "",
inputVal_8: "",
inputVal_9: "",
inputVal_10: ""
};
}
handleInput1Change = (e) => {
this.setState({inputVal_1: e.target.value});
}
handleInput2Change = (e) => {
this.setState({inputVal_2: e.target.value});
}
handleInput3Change = (e) => {
this.setState({inputVal_3: e.target.value});
}
handleInput4Change = (e) => {
this.setState({inputVal_4: e.target.value});
}
handleInput5Change = (e) => {
this.setState({inputVal_5: e.target.value});
}
handleInput6Change = (e) => {
this.setState({inputVal_6: e.target.value});
}
handleInput7Change = (e) => {
this.setState({inputVal_7: e.target.value});
}
handleInput8Change = (e) => {
this.setState({inputVal_8: e.target.value});
}
handleInput9Change = (e) => {
this.setState({inputVal_9: e.target.value});
}
handleInput10Change = (e) => {
this.setState({inputVal_10: e.target.value});
}
cancelCourse = () => {
this.setState({
inputVal_1: "",
inputVal_2: "",
inputVal_3: "",
inputVal_4: "",
inputVal_5: "",
inputVal_6: "",
inputVal_7: "",
inputVal_8: "",
inputVal_9: "",
inputVal_10: ""
});
}
render() {
return (
<form>
<input value={this.state.inputVal_1} onChange={this.handleInput1Change} />
<input value={this.state.inputVal_2} onChange={this.handleInput2Change} />
<input value={this.state.inputVal_3} onChange={this.handleInput3Change} />
<input value={this.state.inputVal_4} onChange={this.handleInput4Change} />
<input value={this.state.inputVal_5} onChange={this.handleInput5Change} />
<input value={this.state.inputVal_6} onChange={this.handleInput6Change} />
<input value={this.state.inputVal_7} onChange={this.handleInput7Change} />
<input value={this.state.inputVal_8} onChange={this.handleInput8Change} />
<input value={this.state.inputVal_9} onChange={this.handleInput9Change} />
<input value={this.state.inputVal_10} onChange={this.handleInput10Change} />
<input type="submit" name="saveCourse" value="Create" />
<input type="button" name="cancelCourse" value="cancel" onClick={this.cancelCourse} />
</form>
);
}
}
ReactDOM.render(<MyApp />, document.getElementById("app"));<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="app"></div>There is a cleaner way to do this though. Rather than having n state properties and n event handlers, one for each input, with some clever coding we can reduce the code dramatically.
In the constructor we just declare an empty object, which will be used to hold input values. We use only one input handler and pass it the index of the input element we want to change the value of. This means that the value of an individual input is generated the moment we start typing into it.
To reset the form, we only need to set our input object back to being empty again.
The input value is this.state.inputVal[i]. If i doesn’t exist (we haven’t typed anything yet into that input) we want the value to be an empty string (instead of null).
cancelCourse = () => {
this.setState({inputVal: {}});
}
render() {
return (
<form>
{[...Array(n)].map(
(item, i) => <input value={this.state.inputVal[i] || ""} onChange={this.handleInputChange.bind(this, i)} />
)}
</form>
);
}
Demo below:
class MyApp extends React.Component {
constructor() {
super();
this.state = {
inputVal: {}
};
}
handleInputChange = (idx, {target}) => {
this.setState(({inputVal}) => {
inputVal[idx] = target.value;
return inputVal;
});
}
cancelCourse = () => {
this.setState({inputVal: {}});
}
render() {
return(
<form>
{[...Array(10)].map( //create an array with a length of 10
(item, i) => <input value={this.state.inputVal[i] || ""} onChange={this.handleInputChange.bind(this, i)} /> //bind the index to the input handler
)}
<input type="submit" name="saveCourse" value="Create" />
<input type="button" name="cancelCourse" value="cancel" onClick={this.cancelCourse} />
</form>
);
}
}
ReactDOM.render(<MyApp />, document.getElementById("app"));<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="app"></div>