clearing the value of an input field in react.js-ag捕鱼王app官网

to clear the value of an input field in react:

1. store the input value in a state variable.
2. when a certain event occurs, set the state variable to an empty string.
3. for uncontrolled components, set the value of ref to an empty string, ref.current.value = '';e.g.

import {usestate} from 'react';

const app = () => {
  // 👇️ 将输入的值存储在状态中
  const [message, setmessage] = usestate('');

  const handlechange = event => {
    setmessage(event.target.value);
  };

  const handleclick = () => {
    // 👇️ 清除 input 值
    setmessage('');
  };

  return (
    <div><inputid="message"name="message"type="text"onchange={handlechange}value={message}
      /><buttononclick={handleclick}>clear fieldbutton>div>
  );
};
exportdefaultapp;

we use usestatethe hook to store the value of the input field in a state variable.

to clear the entered value, we have to set the message status variable to an empty string.

every time the button is clicked, the function we passed to onclickthe attribute of the button element will be called handleclick.

the button can be a submit button for a form, or a simple button that triggers an event.

this method can be used to reset the values ​​of as many input fields as needed.

userefif we use an uncontrolled component via the hook, set the value of ref to an empty string.

import {useref} from 'react';

const app = () => {
  const ref = useref(null);

  const handleclick = () => {
    // 👇️ 清除 input 字段值
    ref.current.value = '';
  };

  return (
    <div><inputref={ref}id="message"name="message"type="text" /><buttononclick={handleclick}>clear fieldbutton>div>
  );
};

this code example achieves the same result, but for an uncontrolled component.

useref()the hook can be passed an initial value as an argument. the hook returns a mutable ref object whose .currentattributes are initialized to the passed argument.

注意, we have to access the current property of the ref object to access the input element on which we set the ref attribute.

when we pass a ref prop to an element, for example , react .currentsets the property of the ref object to the corresponding dom node.

this method can be used to clear the values ​​of as many uncontrolled input fields as needed.

alternatively, when using uncontrolled input fields, we can also use reset()the method to clear the values ​​of all input fields in the form.

import {useref} from 'react';

const app = () => {
  const firstref = useref(null);
  const lastref = useref(null);

  const handlesubmit = event => {
    console.log('handlesubmit ran');
    event.preventdefault();

    // 👇️ 清除表单中的所有输入值
    event.target.reset();
  };

  return (
    <div>
      <form onsubmit={handlesubmit}>
        <input
          ref={firstref}
          id="first_name"
          name="first_name"
          type="text"
        />
        <input
          ref={lastref}
          id="last_name"
          name="last_name"
          type="text"
        />
        <button type="submit">submit formbutton>
      form>
    div>
  );
};

export default app;

注意, this approach does not work for controlled components where we store the value of the input field in the state.

we handlesubmitused event.preventdefault()a method in the function to prevent the page from refreshing when the form is submitted.

reset()method restores the default values ​​of form elements.

no matter how many uncontrolled input fields our form has, reset()a single call to the method will clear all of them.