I have a ponent with a state: {likes: 123} I display the number of likes next to a 'like' button. How do I implement a functionality to this button, so when I click it once, it adds to likes (so state.likes = 124), then if I want to click it a second time it goes back to previous state (state.likes = 123). Of course, it displays the correct number of likes at all times. Here's what I've got so far:

class ProfileInfo extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      likes: this.props.likes,
    };
  }
  handleLike = () => {
    this.setState(prevState => ({
      likes: prevState.likes + 1,
    }));
  }
  render() {
    return (
      <div>
        <button className="like-button" onClick={this.handleLike}>
          Like
        </button>
      </div>
    );
  }
}

export default ProfileInfo;

I have a ponent with a state: {likes: 123} I display the number of likes next to a 'like' button. How do I implement a functionality to this button, so when I click it once, it adds to likes (so state.likes = 124), then if I want to click it a second time it goes back to previous state (state.likes = 123). Of course, it displays the correct number of likes at all times. Here's what I've got so far:

class ProfileInfo extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      likes: this.props.likes,
    };
  }
  handleLike = () => {
    this.setState(prevState => ({
      likes: prevState.likes + 1,
    }));
  }
  render() {
    return (
      <div>
        <button className="like-button" onClick={this.handleLike}>
          Like
        </button>
      </div>
    );
  }
}

export default ProfileInfo;

It just adds likes on and on.

• javascript
• reactjs
• frontend

• What have you tried so far? Please show your code. – Soviut Commented Sep 4, 2017 at 21:52
• I;ve edited my first post – user7605119 Commented Sep 4, 2017 at 21:56

1 Answer 1

You could do something like the following.

Here is a codesandbox with a more plete version of the code.

import React from 'react';

class Likes extends React.Component {

  constructor(props){

    super(props);
    this.state = {
      likes: 124,
      updated: false
    };

  }

  updateLikes = () => {

    if(!this.state.updated) {
      this.setState((prevState, props) => {
        return {
          likes: prevState.likes + 1,
          updated: true
        };
      });

    } else {

      this.setState((prevState, props) => {
        return {
          likes: prevState.likes - 1,
          updated: false
        };
      });

    }
  }

  render(){

    return(
      <div>
        <p onClick={this.updateLikes}>Like</p>
        <p>{this.state.likes}</p>
      </div>
    );
  }
}

export default Likes;