提交表单后清空输入

Question

I'm trying to empty the input tag once I'm updating my state:

state = {
    formName: '',
    inputs: [],
    tempInput: {
      inputLabel: '',
      inputType: '',
      inputValue: ''
    }
  };

this is my form:

  <div className="formG">
        <form className="form-maker" onSubmit={this.handleSubmit}>
          Label:
          <input name="inputLabel" type="text" onChange={this.handleChange} />
          Type:
          <input name="inputType" type="text" onChange={this.handleChange} />
          Value
          <input name="inputValue" type="text" onChange={this.handleChange} />
          Form Name
          <input name="formName" type="text" onChange={this.formName} />
          <button>Submit</button>
        </form>

that's how I handle the change

 handleChange = e => {
    const { name, value } = e.target;
    this.setState(currentState => ({
      tempInput: { ...currentState.tempInput, [name]: value }
    }));
  };

and I tried to just empty the tempInput but it doesn't work, anybody knows why?

 handleSubmit = e => {
    e.preventDefault();
    const inputs = [...this.state.inputs, this.state.tempInput];
    const { tempInput } = this.state;
    tempInput.inputLabel = '';
    tempInput.inputType = '';
    tempInput.inputValue = '';
    this.setState({ inputs, tempInput });
  };

Answer 1

Your form is an uncontrolled component, so they are not controlled by the state fields. That's why your approach didn't work. Instead you can do e.target.reset() which will clear the entire form. But if you want to reset some input, you can access them and set the .value to "" as I had shown below.

An uncontrolled component works like form elements do outside of React. When a user inputs data into a form field (an input box, dropdown, etc) the updated information is reflected without React needing to do anything. However, this also means that you can't force the field to have a certain value. From Doc

So your handleSubmit method will look like:

handleSubmit = e => {
  e.preventDefault();
  const inputs = [...this.state.inputs, this.state.tempInput];
  // ....
  // The below will reset entire form.
  // e.target.reset();
  // If you want some of them to empty.
  const { elements } = e.target
  elements['inputLabel'].value = "";
  elements['inputType'].value = "";
  elements['inputValue'].value = "";
};

Check the doc of HTMLFormElement.elements

Answer 2

Your input tags are not displaying the value of your state. 1) pull the individual values out of tempInput 2) use the value stored in your state that is then updated by your handleChange. 3) In your handleSubmit function reset your individual values to and empty string.

your handleChange should look like:

handleChange = e => {
     const { name, value } = e.target;
     this.setState([name]: value);
};

your jsx should look like :

<form className="form-maker" onSubmit={this.handleSubmit}>
      Label:
      <input name="inputLabel" value={this.state.inputLabel} type="text" onChange={this.handleChange} />
      Type:
      <input name="inputType" value={this.state.inputType}  type="text" onChange={this.handleChange} />
      Value
      <input name="inputValue" value={this.state.inputType} type="text" onChange={this.handleChange} />
      Form Name
      <input name="formName" value={this.state.formName} type="text" onChange={this.formName} />
      <button>Submit</button>
    </form>

Answer 3

You're mutating the original state. You can copy and then only set the state. Just changing the following will work fine for you.

Replace this:

const { tempInput } = this.state;

With this:

const { tempInput } = {...this.state}; // copy the state

Also, be sure to bind the state value in your input elements like this to make them controlled component:

<input name="inputLabel" type="text" 
  onChange={this.handleChange} 
  value={this.state.tempInput.inputLabel || ''} />

And your handler should be:

handleChange = e => {
     const { value } = e.target;
     this.setState({value}); 
// now, value will correspond to the controlled component
};

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Also take care react suggest to use controlled component as far as possible:

In most cases, we recommend using controlled components to implement forms.