TIL12 - JS - Intro

JavaScript Intro

1. Printing to Console

console.log();

In Javascript, it is a good practice to end all lines of code with ;

2. Comments

//

• Comments out a single line
  > ex)

//Print 5 to console
console.log(5);

• Can also be used to add comment at the end of a line of code
  > ex)

console.log(5); //Prints 5 to console

/* Comments */

• Comments out multiple lines
  > ex)

/* This is
an example of
commenting out multiple lines */

• Can also be used to add comment within a line of code
  > ex)

console.log(/* Print this value */ 5);

3. Data Types

In Javascript, there are 7 fundamental data types:

• Number
• String
• Boolean
• Null
• Undefined
• Symbol
• Object

*The first 6 of the above are primitive data types
*The Object data type is more complex

4. Properties & Methods

Objects, including instances of data types, in Javascript have unique properties and methods that can be called on to implement various functions

properties & methods of an object are called with the . operator

Properties
Properties are unique features of an object

• properties are called with the following syntax:
  obejct/instance name + . + property name
• ex) 'hello'.length
  Here, .length is a property of the string instance 'hello'
  > calling 'hello'.length with console.log() will print the length of the string 'hello' to the console

Methods
Methods are unique actions you can perform on an object

• methods are called with the following syntax:
  obejct/instance name + . + property name + ()
• ex) console.log()
  Here, .log() is a method of Javascript's built-in obejct console
• ex) 'hello'.toUpperCase()
  Here, .toUpperCase() is a method for the string object instance 'hello'

5. Built-in Objects

Javascript provides objects 'built-in' to the language, like Math obejct, which are a collection of properties and methods that can be accessed to perform tasks