Angular: ReferenceError: 'function' is not defined

Question

I have a simple Plunkr app that adds two numbers together on the click of a button.

I am getting a ReferenceError: addNumber is not defined where add number is a function that is called by the 'onClick' handler.

onClick(num1, num2){
  addNumber(num1, num2).then((result) => this.result = result));
}

addNumber(x, y){
  return new Promise((resolve) => {
          x = parseInt(x);
          y = parseInt(y);
          setTimeout(() => resolve(x+y), 2000)
        })
      }
    }

However, if I add the function keyword to addNumber it works but as I understand it, with Typescript it is optional to use the function keyword.

Why is addNumber not defined when the button is clicked?

Saravana · Accepted Answer · 2017-06-23 08:40:03Z

2

When accessing class members you have to reference them using this:

this.addNumber(num1, num2).then((result) => this.result = result));

When you add the function keyword to addNumber you are making it a local function instead of a class member thus making it accessible without the this reference.

edited Jun 23, 2017 at 8:40

answered Jun 23, 2017 at 8:38

Saravana

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3 Comments

Sajeetharan Over a year ago

what is the difference ?

Saravana Over a year ago

Didn't see yours. Mine explains why adding function before it works.

user9030 Over a year ago

I chose this one as the answer because although the solution is the same as @Sajeetharan's, you explain what the problem was

mayur · Accepted Answer · 2017-06-23 08:39:11Z

2

Use this for existing class self functions

onClick(num1, num2) {
  this.addNumber(num1, num2).then((result) => this.result = result));
}

edited Jun 23, 2017 at 8:39

mayur

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answered Jun 23, 2017 at 8:36

Sajeetharan

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