Encountering a "TypeError: Cannot read property 'push' of undefined" in Angular 2

Question

Encountering a "TypeError: Cannot read property 'push' of undefined" in Angular 2

I have been working on an Angular2 component where I declared an array of strings and initialized it at the same time. However, I encountered an error of 'undefined' when I tried to push data in one of the methods. I am unsure about what I might be missing!

export class MyComponent implements OnInit {

    public categoryData: string[] = [];

    ngOnInit(): void {

    }

    public loadDataFromServer() {

        let MyServerData = result.data;

        MyServerData.forEach(function (item) {
            this.categoryData.push(item.BarTitle); // error here
        });
    }
}

error

ERROR TypeError: Cannot read property 'categoryData' of undefined

angular typescript

Answer 1

Answer №1

In order to maintain the proper context of this, it is necessary to utilize an arrow function instead of a new anonymous function created with the function keyword:

MyServerData.forEach((item) => {
  this.categoryData.push(item.BarTitle); // this line will execute without errors
});

Answer 2

In order to maintain the proper context of this, it is necessary to utilize an arrow function instead of a new anonymous function created with the function keyword:

MyServerData.forEach((item) => {
  this.categoryData.push(item.BarTitle); // this line will execute without errors
});

Answer 3

Answer №2

Try out this code snippet for successful execution:

export class MyComponent implements OnInit {

public categoryData:string[] = [];

ngOnInit(): void {

}

 public fetchDataFromServer() {

        let serverData = result.data;
        const currentData = this;
        serverData .forEach(function(item){
            currentData.categoryData.push(item.BarTitle); // issue resolved
        });
    });
}

Answer 4

Try out this code snippet for successful execution:

export class MyComponent implements OnInit {

public categoryData:string[] = [];

ngOnInit(): void {

}

 public fetchDataFromServer() {

        let serverData = result.data;
        const currentData = this;
        serverData .forEach(function(item){
            currentData.categoryData.push(item.BarTitle); // issue resolved
        });
    });
}

Encountering a "TypeError: Cannot read property 'push' of undefined" in Angular 2

error

Answer №1

Answer №2

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