#JavaScript

Variable declaration in JS

• let
  • It has a block-scope
• const
  • Used for unchanging variable
  • This can’t be re-defined
• var
  • No block-scope
  • var variables are either function-wide or global
  • they are visible through blocks.
• let and const basically replace var.
• var should not be used anymore

Loops in Javascript

• for loop
  • Execute code a certain amount of times (with counter variable)
• for-of loop
  • Execute for every element in an array
• for-in loop
  • Execute for every key in an object
• while loop
  • Execute code as long as a condition is true

Exception

• An exception signifies the presence of an abnormal condition which requires special operable techniques
• Error Types
  • Syntax Error
    • Mistake in the pre-defined syntax
  • Runtime Error
    • Runtime errors are known as Exceptions.
  • Logical Error
    • Logical mistake in the program, abnormal output

Advance part in Functions

• Functions are special type of Objects

Function stored in Object

• Function as Methods
• Function stored in an object termed as Methods

const person = {
  age: 20
  greet: function greet(){
    console.log('Methods')
  }
}
person.greet()