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JavaScript Functions

Functions Study Path

Learn Functions in the Right Order:

  • First the idea
  • Then how to make them
  • Then how to use them

Step 1Beginner

What are Functions?

  • Functions are reusable code blocks designed for particular tasks
  • Functions are executed when they are called or invoked
  • Functions are fundamental in all programming languages


Step 2Beginner

Calling Functions

  • Functions are executed when they are called or invoked
  • You call a function by adding parentheses to its name: name()


Step 3Beginner

Function Parameters

  • Parameters allow you to send values to a function
  • Parameters are listed in parentheses in the function definition


Step 4Beginner

Function Return Values

  • A function can return a value back to the code that called it
  • The return statement is used to return a value from a function


Step 5Intermediate

Function Arguments

  • Function parameters and arguments are distinct concepts
  • Parameters are the names listed in the function definition
  • Arguments are the values received by the function


Step 6Intermediate

Function Expressions

  • A function expression is a function stored in a variable
  • The variable name can be used to call the function


Step 7Intermediate

Arrow Functions

  • Arrow Functions is a short syntax for function expressions
  • You can skip the function keyword
  • You can skip the return keyword
  • You can skip the curly brackets


Step 8Intermediate

Function Quiz

  • Test your knowledge of JavaScript functions
  • The quiz uses the examples you learned in the tutorial
  • .


Advanced Functions Study Path


Step 1Advanced

JavaScript Definitions

  • Function declarations
  • Function Expression
  • Arrow Functions
  • Function Constructors

Step 2Advanced

JavaScript Callbacks

A JavaScript callback is a function passed as an argument to another function, which is then executed (or "called back") at a later point in time to complete a specific task.


Step 3Advanced

The this Keyword

How this works (especially inside objects).

How this is decided by how it is called.


Step 4Advanced

The call() Method

Call a function with a chosen this.

Pass a list of arguments.


Step 5Advanced

The apply() Method

Call a function with a chosen this.

Pass an array of arguments.


Step 6Advanced

The bind() Method

Call a function with a chosen this.

Use bind() when you need a function to run later with the same this.


Step 7Advanced

Self Invoked - IIFE

Self-starting functions.


Step 8Advanced

JavaScript Closures

Functions that remember their scope

Learn how functions can remember variables after the outer function finishes.


Step 9Advanced

Function References

Function Object Methods & Properties.



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