Get variable outside scope from a function inside an object - Javascript

Question

I have a function inside an object inside a Class.

The object of the class is initialized and I want to call the function, but the function need a variable defined on the constructor of the Class.

class someClass {
  constructor() {
    this.foo = "bar";

    this.print = {
      variable: function() {
        console.log(this.foo);
      }
    };

  }
}

// And I call it from the global scope

var someObject = new someClass();

someObject.print.variable();

It will print

undefined

I know is a different scope and maybe I can't access to it.

The objective of this is to have some order with my functions.

I want to access to my function like someObject.print.variable();

Not exactly the same situation, but the exact same set of answers applies: stackoverflow.com/questions/20279484/… — Ry-
– Ry- ♦, Commented Mar 3, 2018 at 0:19

Barmar · Accepted Answer · 2018-03-03 00:15:11Z

5

Use an arrow function, it will be bound to the original this in the object that defined it.

class someClass {
  constructor() {
    this.foo = "bar";

    this.print = {
      variable: () => {
        console.log(this.foo);
      }
    };

  }
}

// And I call it from the global scope

var someObject = new someClass();

someObject.print.variable();

answered Mar 3, 2018 at 0:15

Barmar

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Comments

willowis.cool · Accepted Answer · 2018-03-03 00:13:36Z

1

Something like this maybe?

<script>
class someClass {
  constructor() {
    let that = this;
    this.foo = "bar";

    this.print = {
     variable: function() {
        console.log(that.foo);
       }    
    };

  }
}

//And I call it from the global scope

var someObject = new someClass();

someObject.print.variable();
</script>

answered Mar 3, 2018 at 0:13

willowis.cool

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2 Comments

BlueSeph Over a year ago

Yes!, I didn't know about I can reference the object in let, Thanks!.

BlueSeph Over a year ago

Sorry, It worked, but the Barmar's answer is cleaner. If I had the priviledge to give upvote I would have given you one.

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