Array.splice not woking when there is one index left-CodePudding

My idea in the code is to handle and store the change on checkbox in array when I uncheck one of the checkboxs It will splice and remove its index. The problem is it will not remove the last index even when it's checkbox is unchecked and its value is false.

The code:

 CheckBoxHandler1(e) {
    let temp = [...this.state.boxes];
    console.log(e.target.checked);
    e.target.checked === false
      ? temp.splice(e.target.value, 1)
      : (temp[e.target.value] = [e.target.checked, e.target.name]);

    this.setState({ boxes: temp, checked: e.target.checked });
    console.log(temp);
    console.log(this.state.boxes);
}

CodePudding user response：

You should probably be storing the state of all the boxes rather than removing them. You can initially start off with an empty object for the array and then update that when each box changes.

const { useEffect, useState } = React;

function Example() {

  const [ boxes, setBoxes ] = useState({});

  // The `handleChange` is on the parent element
  // so we need to extract the nodeName, the name of
  // the checkbox, and it's status, and then if we've
  // actually un/checked a box, update the state.
  function handleChange(e) {
    const { nodeName, checked, name } = e.target;
    if (nodeName === 'INPUT') {
      setBoxes({ ...boxes, [name]: checked });
    }
  }

  // This just confirms the state has been updated
  useEffect(() => console.log(boxes), [boxes]);

  return (
    <div onChange={handleChange}>
      Name: <input name="name" type="checkbox" checked={boxes.name} />
      Age: <input name="age" type="checkbox" checked={boxes.age} />
      Job: <input name="job" type="checkbox" checked={boxes.job} />
    </div>
  );

};

ReactDOM.render(
  <Example />,
  document.getElementById('react')
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.production.min.js"></script>
<div id="react"></div>

Class component:

const { Component } = React;

class Example extends Component {

  constructor() {
    super();
    this.state = {};
    this.handleChange = this.handleChange.bind(this);
  }

  handleChange(e) {
    const { nodeName, checked, name } = e.target;
    if (nodeName === 'INPUT') {
      this.setState({ ...this.state, [name]: checked }, () => {
        console.log(this.state)
      });
    }
  }

  render() {
    return (
      <div onChange={this.handleChange}>
          Name: <input name="name" type="checkbox" checked={this.state.name} />
          Age: <input name="age" type="checkbox" checked={this.state.age} />
          Job: <input name="job" type="checkbox" checked={this.state.job} />
      </div>
    );
  }

};

ReactDOM.render(
  <Example />,
  document.getElementById('react')
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.production.min.js"></script>
<div id="react"></div>