Pass variable in react

Question

I have his code where i try to pass a variable to the handleclick fcn and set state to that variable:

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      name: 'Initial State'
    };
    this.handleClick = this.handleClick.bind(this);
  }
  handleClick(temp) {
    this.setState({
      name:temp
    });
  }
  render() {
    return (
      <div>
        <button onClick={this.handleClick('name')}>Click Me</button>
        <h1>{this.state.name}</h1>
      </div>
    );
  }
};

It doesn't work, can someone explain how to pass a variable and set state to it, if it's possible??

Tholle · Accepted Answer · 2018-11-04 21:42:06Z

2

By writing this.handleClick('name') you are invoking the handleClick function directly on render. You want to give a function to the onClick prop that will be invoked on click.

Example

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      name: "Initial State"
    };
    this.handleClick = this.handleClick.bind(this);
  }
  handleClick(temp) {
    this.setState({
      name: temp
    });
  }
  render() {
    return (
      <div>
        <button onClick={() => this.handleClick("name")}>Click Me</button>
        <h1>{this.state.name}</h1>
      </div>
    );
  }
}

ReactDOM.render(<MyComponent />, document.getElementById("root"));

<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="root"></div>

answered Nov 4, 2018 at 21:42

Tholle

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4 Comments

Jrobm2k9 Over a year ago

Awesome, thank you!i tried marking this as the answer but i have to wait 10 mins

Estus Flask Over a year ago

This will result in creating an arrow on each render which is undesirable if it's possible to avoid this.

Jrobm2k9 Over a year ago

So what would be a better solution?

Tholle Over a year ago

@Jrobm2k9 Don't worry about it. If your use case absolutely demands that you prematurely optimize it, you can use a data attribute.

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