Angular 4 typescript: Cannot read property 'list' of undefined

Question

I'm initializing an array and trying to push elements into the array. But I get this error saying Cannot read property 'list' of undefined.

list: Array<any> = [];
this.data.forEach(function(element) {
      this.list = [];

    });
    this.data.forEach(function(element) {

        this.list.push({
          'name' : this.url
        })
  });

Even though I'm initializing the array, it is saying as undefined

use an arrow function to preserve the "this" context like (element) => { } instead of function(element) { } — bryan60
– bryan60, Commented Apr 20, 2018 at 16:58

bryan60 · Accepted Answer · 2018-04-20 17:06:14Z

2

use an arrow function to preserve the "this" context like

(element) => { }

instead of

function(element) { }

arrow functions don't create new scope, regular functions do, so "this" refers to the function scope (where list is undeclared) in a normal function declaration rather than the component scope (where list is declared) like you want.

generally, you will be using arrow functions much more often than not. regular function declaration is the more specialized case.

edited Apr 20, 2018 at 17:06

answered Apr 20, 2018 at 16:59

bryan60

29.5k5 gold badges56 silver badges71 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Angular 4 typescript: Cannot read property 'list' of undefined

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related