javascript - In what object does Node.js store variables?

Question

in my server.js:

If I type:

var yo = 123;
console.log(global.yo); // undefined
console.log(this.yo); // undefined

in the browser this would be window.yo, so is there some object in Node where this variable is stored?

Answer 1

JavaScript, regardless whether on the browser or on the server, does not store local declared variables on any object, they just exist in the scope (and cannot be accessed as properties on anything).

The only exception are global variables, which are accessible as properties of the global object (a language term). In browsers, that object is exposed as window, in Node it is exposed as global. It also is the value of the this binding in global code.

As stated in the other answers, a file executed with node is not global code, but lives in a module scope, so you usually won't observe this behaviour for any declared variables. It works in the REPL, though:

$ node
> var yo = 123;
> global.yo
123
^C
$ echo "var yo = 123; console.log(global.yo)" > test.js
$ node test.js
undefined
$ echo "yo = 123; console.log(global.yo)" > test.js
$ node test.js
123