title: Concat vs push adding new array in react best practice
body: <p>Many folks promote immutability because they use redux altogether with react, but I'm still seeing people using push instead of concat.</p>
  
  <p>Take this code for example:</p>
  
  <pre><code>submitComment() {
    console.log('submitComment: '+JSON.stringify(this.state.comment))
  
    APIManager.post('/api/comment', this.state.comment, (err, response) =&gt; {
      if (err){
        alert(err)
        return
      }
  
      console.log(JSON.stringify(response))
      let updateList = Object.assign([], this.state.list)
      updatedList.push(response.result)
      this.setState({
        list: updatedList
      })
    })
  }
  </code></pre>
  
  <p>in this case does it matter at all? What's the issue with push above?</p>