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JavaScript

Posted by Kristian Woods
Kristian Woods
23,414 Points

How do you set an active state on one component at a time, and remove the active state on all others in React?

I have a basic application, where I click on a dot and it changes the colour to red. I have two dots. However, I want to be able to click on one, give it its active state, then disable the active state the other dot. Currently, I have it working. However, I don't feel confident its the right approach.

In the Dot component, I have logic to set an 'activeDot' class 

className={"dot " + (this.props.isActive ? "activeDot" : "")}

I have a function in the main parent component 'handleDot'

handleDot = id => {
    var state = Object.assign({}, this.state);
    for (let i = 0; i < this.state.dots.length; i++) {
      if (i === id) {
        state.dots[i].isActive = true;
      } else {
        state.dots[i].isActive = false;
      }
    }
    this.setState(state);
  };

Here is a link to the project

https://codesandbox.io/s/sad-grothendieck-1q319

is there a better way to approach this?

Thanks in advance

1 Answer

Kristian Woods
Kristian Woods
23,414 Points
Kristian Woods
Kristian Woods
23,414 Points

solution:

  handleDot = id => {
    this.setState(prevState => ({
      dots: prevState.dots.map((dot, i) => ({
        ...dot,
        isActive: i === id
      }))
    }));
  };