1. Scope #

Created Tuesday 14 July 2020

Scopes in JS #

There are 4 scopes in JS, in order of lookup(during use):

1. Local scope - block scope, function scope.
2. Enclosing scope - inner function’s scope.
3. Global scope - variables/functions at the script level, i.e outside of any class/function. This scope is unique.
4. Built-in - stuff loaded by the intepreter, like console.log() etc. You can hack it.

Note:

• Root Scope - global scope of the browser.

• Exactly like python3(LEGB), except that writing to outer variable is not restricted.

Popular global objects(for the browser) #

• window - browser object. Controls the whole window - manipulate owned tabs, close the browser. This is unique.
• document - current webpage object. Used for DOM manipulation. Each page has a document object.

Note: Node.js has neither, simply because both window and webpage are irrelevant to an standalone intepreter.