My array is undefined Angular2

Question

I want put 10 numbers in my Array , but I get undefined

public arrayDrag: number[];

ngOnInit() {
    this.arrayDrag = new Array(); //or   this.arrayDrag = new Array(10)
}

  rowDragEnd(event) {
    let max = 0;
    this.arrayDrag = new Array();  //or   this.arrayDrag = new Array(10)

    this.gridApi.forEachNodeAfterFilterAndSort(function(node) {
      if (max < 10) {
        this.arrayDrag.push(node.data.point);
        console.log('add', node.data.point);
        max += 1;
      }
    });
  }

I declared to arrayDrag with (0) or (10) and when my event is calls (rowDragEnd), I get error "undefined" the this.arrayDrag.push(

What's the full error? Are you sure that the issue isn't node.data.point? — random_user_name
– random_user_name, Commented May 30, 2018 at 14:55
Possible duplicate of How to access the correct `this` inside a callback? — Martin Parenteau
– Martin Parenteau, Commented May 30, 2018 at 15:07

Teddy Sterne · Accepted Answer · 2018-05-30 14:55:50Z

6

You need to use an arrow function to maintain the scope to your component.

this.gridApi.forEachNodeAfterFilterAndSort((node) => {
  if (max < 10) {
    this.arrayDrag.push(node.data.point);
    console.log('add', node.data.point);
    max += 1;
  }
});

In the code you posted you are using a function so this refers to the function and not your component.

answered May 30, 2018 at 14:55

Teddy Sterne

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2 Comments

EduBw Over a year ago

Perfect, thanks, But I don't understand why with function () {} undefined ... can you tell me ?

Teddy Sterne Over a year ago

When you declare a function as function () {} within the function this refers to the function and not the component so the function does not have a property of arrayDrag. When you declare the function as () => {} then within the function this refers to the outer scope.

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