CODEWITHSUNDEEP
javascriptnode.js
Raanan W
Raanan W

Reputation: 1295

Function execution context, browser vs. nodejs

The following function provides two different results, in Node and Browser:

(function funfunfun(root, factory) {
    console.log(root === this);
    factory(root);
})(this, function (root) {
    console.log(root === this);
});

In node, it will output false twice. In the browser it will output true twice, as I would expect.

So the question is... why?

Upvotes: 3

Views: 285

Answers (2)

Subin Sebastian
Subin Sebastian

Reputation: 10997

In a browser, within an unbound function, this will point to window object. Thats why you are getting two trues in browser.

Now in nodejs equalent of window is global. If you run this===global you will get true in repl.

But from file this is not equal to global.
global variable assignment in node from script vs command line

Upvotes: 5

Vasan
Vasan

Reputation: 4956

This might already be known, but just wanted to add to @Subin's answer that if you explicitly bind the functions to the same this, it will return true whether inside script or REPL.

(function funfunfun(root, factory) {
    console.log(root === this);
    factory(root);
}).call(this, this, (function (root) {
    console.log(root === this);
}).bind(this, this));

Also, this answer provides good info on the global object.

Upvotes: 2

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