How to merge two array of objects with reactjs?

Question

I have a react-big-calendar, I want to fetch the events of this week from the backend and the other weeks from the local storage.

My code is :

componentDidMount() {
    fetch("url")
    .then(Response => Response.json())
      .then(data => {
        let evts = data;
        for (let i = 0; i < evts.length; i++) {
          evts[i].start = moment(evts[i].start).toDate();
          evts[i].end = moment(evts[i].end).toDate();
          this.state.evt1.push(evts[i])
        }                   
        this.setState({
          evt1: evts,
          prevEvents : evts
        })
      }) 
      console.log(this.state.evt1)
      const cachedHits = JSON.parse(localStorage.getItem('Evènements')) 
      console.log(cachedHits)
      for (let j = 0; j <cachedHits.length; j++) {
        cachedHits[j].start = moment(cachedHits[j].start).toDate();
        cachedHits[j].end = moment(cachedHits[j].end).toDate();
        this.state.evt2.push(cachedHits[j])
      }
    this.setState( {
      evt2: this.state.evt2
  })
    this.setState({
      events: [...this.state.evt1, ...this.state.evt2]
    })
  console.log(this.state.events)
  }

the events is the merged array of evt1 (events from the backend) and evt2 (events from the localstorage), when I run it, I get on my console :

The evt1 are :

The evt2 are :

But, on my calendar, just the evt2 are displayed and not all the events (evt1 and evt2).

How can display all the events on my calendar ?

Answer 1

You can use spread operator to merge two array.

var a = [{fname : 'foo'}]
var b = [{lname : 'bar'}]
var c = [...a, ...b] // output is [{fname : 'foo'},{lname : 'bar'}]