For loop doesn't work in array (Javascript, Angular 2)

Question

I have an array that contains cameras specifications, the problem occurs when I try to run a for loop to get the elements.

Here is the content of my array :

I tried all different types of for loops like forEach, basic for loop with increment or for (let item of myArray)

For loop doesn't run and I have no return of the element in the array.

for (let id in elements) {

      if (typeof elements[id].brands !== 'undefined') {

        delete this.items;

        let itemsArray = [];

        for (let elementData of elements[id].brands) {

          this.http.get("assets/data/" + elementData + "Reflex.json").map(res => res.json()).subscribe(data => {

            Array.prototype.push.apply(itemsArray, data);

          });

        }

        this.items = itemsArray;

      }

      if (typeof elements[id].sensorSize !== 'undefined') {


      }

    }

(this.items is the array that you can see on the top (I use Angular2)).

You are probably getting `this.items` through an http call and it's undefined by the time your code reaches to the loop. — eko, Jan 17 '17 at 10:49
@torazaburo this output me a 0 so for him the length of the array is 0 — Alvin FREY, Jan 17 '17 at 10:55
You should post your entire script, I don't think the problem comes from the for loop (or we should all stop working with JS and go on strike...), but from the items list that is not filled with values. — Ripley511, Jan 17 '17 at 11:02
Problem is in your `this` most likely. Please use `console.log(this)` and tell us if it references the proper object. — Dellirium, Jan 17 '17 at 11:07
@Ripley511 I post a little bit more of my script on the main message — Alvin FREY, Jan 17 '17 at 11:08
You do realize that `this.http.get` is an http call as I've said in my first comment right? — eko, Jan 17 '17 at 11:10
@Dellirium ReflexPage {modalCtrl: ModalController, http: Http, items: Array[0]} and when i expand it : items:Array[8] — Alvin FREY, Jan 17 '17 at 11:10
@AlvinFREY so your items is an empty array, not the one you posted in the shot, which means the loop works, you are just looping through an empty array. — Dellirium, Jan 17 '17 at 11:11

score 0 · Answer 1 · answered Jan 17 '17 at 10:53

0

Try this code, it will iterate on the array itself and return all items in it as objects in the inline function.

this.items.forEach( function (item)
{
 item.xxx=11;
} );

answered Jan 17 '17 at 10:53

Miro Krsjak

355
1
16

When I started to edit the answer in my mobile phone,there were no posts yet, so did not know someone is writing the same. – Miro Krsjak Jan 17 '17 at 10:56
@torazaburo sry..the comment was directed at Miro – Suraj Rao Jan 17 '17 at 11:03
I would just let him try it ;) peace – Miro Krsjak Jan 17 '17 at 11:05

score 0 · Answer 2 · answered Jan 17 '17 at 11:16

  this.http.get("assets/data/" + elementData + "Reflex.json").map(res => res.json()).subscribe(data => {

    Array.prototype.push.apply(itemsArray, data);

  });

This call is the problem.It is asynchronous.

The for loop will not wait for the response to push data into itemArray. A rough way to get the array is:

      this.http.get("assets/data/" + elementData + "Reflex.json").map(res => res.json()).subscribe(data => {

        Array.prototype.push.apply(this.items, data);//make sure this.items is set to empty previous to call

      });

For loop doesn't work in array (Javascript, Angular 2)

2 Answers2