ReactJS - Need to click twice to set State and run function

Question

Here is a summary of the code I have inside my React component:

getInitialState: function(){
  return{link:""}
},
onClick1: function(){
   this.setState({link:"Link1"});
   this.otherFunction();
},
onClick2: function(){
   this.setState({link:"Link2"});
   this.otherFunction();
},
otherFunction:function(){
     //API call to this.state.link
},
render: function(){
  return <div>
  <button1 onClick={this.onClick1}>Link1</button>
  <button2 onClick={this.onClick2}>Link2</button>
  //...some code to display the results of API call
  </div>
  }

The problem I have is that the first time I click the button, the otherFunction will run, but it will not have the updated value of myState. If I click a second time, then it works correctly.

`setState` is triggering the render; what is `otherFunction` and what state is it supposed to be updating? — Josh David Miller, Jan 14 '16 at 22:22
there is another state for the API data. That is what the function is updating. I did not include it here because I didn't think it was related. — Marie Pelletier, Jan 14 '16 at 23:29

score 12 · Answer 1 · edited Jun 20 '20 at 09:12

12

From the docs:

setState() does not immediately mutate this.state but creates a pending state transition. Accessing this.state after calling this method can potentially return the existing value.

There is no guarantee of synchronous operation of calls to setState and calls may be batched for performance gains.

If you want a function to execute after the state transition completes, pass it in as a callback:

onClick1: function() {
   this.setState({link:"Link1"}, this.otherFunction);
},

edited Jun 20 '20 at 09:12

Community

1
1

answered Jan 14 '16 at 22:33

Michael Parker

12,724
5
37
58

thanks for the explanation. Unfortunately, putting the function as a callback does not work. EDIT: I have seen some examples and it sounds like it should work. Not sure why mine isn't. I will look it over again. – Marie Pelletier Jan 14 '16 at 23:20
1

Somewhat unrelated, `otherFunction` might be unbound; this might be better: `this.SetState(/*...*/, () => this.otherFunction() )`. – Josh David Miller Jan 14 '16 at 23:32

score 2 · Answer 2 · answered Jan 15 '16 at 01:49

Well, here I am answering my own question, for future reference. I figured it out. I removed this.otherFunction() from the onClick functions, and put it in componentWillUpdate. So it looks like this:

getInitialState: function(){
  return{link:""}
},
onClick1: function(){
   this.setState({link:"Link1"});
},
onClick2: function(){
   this.setState({link:"Link2"});
},
otherFunction:function(){
     //API call to this.state.link
},
componentWillUpdate(){
    this.otherFunction();
},
render: function(){
  return <div>
  <button1 onClick={this.onClick1}>Link1</button>
  <button2 onClick={this.onClick2}>Link2</button>
  //...some code to display the results of API call
  </div>
  }

score 1 · Answer 3 · answered Aug 07 '17 at 13:30

1

If all that onClick does is change the state, then you shouldn't have two functions that do the same job. You should have the new value of the "link" state passed as an argument to the function "onClick" :)

answered Aug 07 '17 at 13:30

Batte Man

63
5

ReactJS - Need to click twice to set State and run function

3 Answers3

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