Global execution context in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Global Execution Context in JavaScript?

It is the default environment where JavaScript code runs first. It creates a global object and sets up the 'this' keyword to refer to that global object.

beginner

What two main phases happen inside the Global Execution Context?

1. Creation phase: JavaScript sets up memory for variables and functions.<br>2. Execution phase: JavaScript runs the code line by line.

beginner

In the Global Execution Context, what does the 'this' keyword refer to?

It refers to the global object, which is 'window' in browsers and 'global' in Node.js.

intermediate

What happens to variables declared with 'var' in the Global Execution Context during the creation phase?

They are hoisted and initialized with 'undefined' before the code runs.

intermediate

How are functions treated differently from variables in the Global Execution Context creation phase?

Functions are hoisted and fully initialized, so they can be called before their declaration in the code.

What is created first when JavaScript runs in the Global Execution Context?

A Creation of function expressions

B Execution of code line by line

C Global object and 'this' keyword setup

D Creation of local variables

The global object and 'this' keyword are set up first during the creation phase of the Global Execution Context.

During the creation phase, what value do 'var' variables get assigned?

A null

B undefined

C 0

D No value assigned

'var' variables are hoisted and initialized with 'undefined' before code execution.

What does the 'this' keyword refer to in the Global Execution Context in a browser?

A The global object (window)

B The current function

C undefined

D The local scope

In the global context in browsers, 'this' refers to the global object called 'window'.

Which phase of the Global Execution Context runs the code line by line?

A Initialization phase

B Creation phase

C Compilation phase

D Execution phase

The execution phase runs the code line by line after the creation phase sets up memory.

Can functions be called before they are declared in the Global Execution Context?

A Yes, because functions are hoisted and fully initialized

B No, functions must be declared first

C Only if declared with 'let'

D Only if declared inside another function

Functions are hoisted and fully initialized during the creation phase, so they can be called before their declaration.

Explain what happens during the creation phase of the Global Execution Context.

Think about what JavaScript prepares before running your code.

Describe the role of the 'this' keyword in the Global Execution Context.

Consider what 'this' points to when you are not inside any function.