DEV Community

loading...

Discussion on: Mini Quiz: Javascript Scoping

Collapse
bakertx profile image
Aaron Baker

The calculateBMI method this mapping to the person object makes sense to me, but the innerFunction mapping to the Window object was a surprise. Anybody care to explain?

Collapse
equiman profile image
Camilo Martinez

Because innerFunction have another different scope. Then this inside reference to function and not to person.

You can solve it adding self:

var person = {
    name: 'Dave',
    weight: 100,
    height: 180,
    calculateBMI: function() {
        console.log(this);
        var self = this;
        function innerFunction() {
            console.log(self);
        }
        innerFunction();
    }
}

Or with arrow function:

var person = {
    name: 'Dave',
    weight: 100,
    height: 180,
    calculateBMI: function() {
        console.log(this);
        let innerFunction = () => {
            console.log(this);
        }
        innerFunction();
    }
}