Pushing items to an array

Question

I have the following variable

var brands = [];

Which I need to populate with some data. The data is comming from an API. I use Axios to perform a GET.

getRemoteBrands() {
    axios
      .get("http://my-url")
      .then(response => {
        response.data.forEach(element => {
          var instance =
          {
            label: element.brand,
            value : element.brand    
          };
          this.brands.push(instance);
        });
      }).catch(error => console.log(error));
  }

The following error is show in developer tools

TypeError: Cannot read property 'push' of undefined
    at index.js:104
    at Array.forEach (<anonymous>)
    at index.js:98

Obviously brands is not an array, but an object. How can I make this an array?

`var brands = [];` creates a *standalone* variable. `this.brands` is not a standalone variable, it's a property of `this`, which is something entirely different (which sounds to be `undefined`) — CertainPerformance, Nov 15 '18 at 09:39
Wow. Javascript 3 Please post an answer and I'll accept that — Tobias Moe Thorstensen, Nov 15 '18 at 09:41
please follow this link to convert object into array. [enter link description here](https://stackoverflow.com/questions/38824349/how-to-convert-an-object-to-an-array-of-key-value-pairs-in-javascript) — Mosam Prajapati, Nov 15 '18 at 09:44

score 1 · Accepted Answer · answered Nov 15 '18 at 09:44

var brands = []; creates a standalone variable. this.brands is not a standalone variable, it's a property of this, which is something entirely different (which sounds to be undefined in your case - you've never assigned anything to this.brands before).

Either refer to the standalone variable brands after creating it:

var brands = [];

class something {
  // ...
  getRemoteBrands() {
    var instance = {
      label: element.brand,
      value : element.brand    
    };
    brands.push(instance);
  }
}

Or create this.brands in the constructor, and refer to this.brands:

class something {
  constructor() {
    this.brands = [];
  }
  getRemoteBrands() {
    var instance = {
      label: element.brand,
      value : element.brand    
    };
    this.brands.push(instance);
  }
}

Pushing items to an array

1 Answers1