How do I call a function from within a nested function in typescript?

Question

I want to call the function func2 from within sample function of function func1. Can someone suggest a way to achieve that?.

class A
{
   public func1()
   {
     let sample = function()
                  {
                    //call func2... but how?
                  }
   }
   public func2()
   {

   }
 }

Thanks in Advance

@Benjamin: Depends on what this refers to inside sample (i.e. how sample is called). — Felix Kling
– Felix Kling, Commented Jan 14, 2017 at 23:20
nop....scope of this is only in func1...not within sample(nested) function. — user3107338
– user3107338, Commented Jan 14, 2017 at 23:23
Related: How to access the correct this inside a callback? — Felix Kling
– Felix Kling, Commented Jan 14, 2017 at 23:27

Tha'er AlAjlouni ثائر العجلوني · Accepted Answer · 2017-01-14 23:34:11Z

47

Use the this keyword with the arrow function notation like this:

class A
{
   public func1()
   {
      let sample = () => 
      {
         this.func2();
      }
   }
   public func2()
   {

   }
 }

The trick is using the arrow function, because the arrow function changes the definition of this to be the instance of the class instead of the current scope.You can read more here

edited Jan 14, 2017 at 23:34

answered Jan 14, 2017 at 23:18

Tha'er AlAjlouni ثائر العجلوني

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6 Comments

Felix Kling Over a year ago

That depends on what this refers to inside sample.

Tha'er AlAjlouni ثائر العجلوني Over a year ago

I updated the answer to fix that by using an arrow function that will use the correct scope.

user3107338 Over a year ago

Awesome.......that works.......could you please explain me how it works?

user3107338 Over a year ago

Its an anonymous function i believe.....but then how is it different from named function......would appreciate if you provide me any link that explains it. Thank you once again.

Felix Kling Over a year ago

@user3107338: Because arrow functions don't have their own this. See stackoverflow.com/q/28371982/218196 and stackoverflow.com/q/34361379/218196 .

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