use concat instead of es6 spread in adding array of object in react

Question

will below code work? Saw it somewhere not sure why the author did that

this.setState({
  messages: this.state.messages.concat({
    text: 'new message'
  })
})

Normally I'll do

this.setState({
  messages: [
    ...this.state.messages,
    {text: 'new messages'}
  ]
})

which one is appropriate?

Nick · Accepted Answer · 2018-06-25 01:21:16Z

1

Either works. concat is more widely supported but if you're using react you're likely transpiling anyway, right? So whichever is more readable to you. I prefer the spread syntax since it's shorter.

Both just make shallow copies. That is, the array object is a new reference, but any objects in the array are the same reference (and value types are copied, as usual).

answered Jun 25, 2018 at 1:21

Nick

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