TIY-Assignments

About JavaScript

Basic Literal Types

null

One of JavaScript’s primitive values. It represents “empty” or “no value”. It can be used when an object can have value but there is currently none.

var nada = null // null

Boolean

One of JavaScript’s primitive values. It is a data type that only has the values “true” or “false”.

Boolean(4>5) // false

Number

One of JavaScript’s primitive values. It is a numerical data.

3.1419

String

One of JavaScript’s primitive values. It is a group of text that is enclosed in either ‘ or “. It is how text is separated from the code that the computer reads.

"This is a string"

Basic Operators

Arithmetic

An operator that takes numerical values as its operands and returns a single number. It follows basic mathematic principles. Uses + - * /

2 + 2 // 4

Comparison

Operators that are used to compare (in various ways) two operands.

• Equality Operators

  == Converts the operands if they are not the same type and then compares them. Ex: 0 == false // true

  != Returns true if the operands are not equal. Ex: 1 != 2 // true

  === Returns true if the operands are equal without conversion. Ex: 1 === '1' // false

  !== Returns true if the operands are not equal and/or not the same type. Ex: 1 !== 2 // true

• Relational Operators > Greater than: Returns true if the left operand is greater than the right. Ex: 2 > 1 // true

  < Less than: Returns true if the left operand is less than the right. Ex: 1 < 2 // true

  >= Greater than or equal to: Returns true if the left operand is greater than or equal to the right. Ex: 1 >= 1 // true

  `<=` Less than or equal to: Returns true if the left operands is less than or equal to the right.
  Ex: `1 <= 2` // `true`
  

Assignment

An operator that assigns a value to the left operand based on the value of the right.

var Stands for variable. It allows values to be assigned to a specific property. Ex: var x = 0 // x === 0

= Assigns the value of the right operand to the left Ex: var zero = 0 // zero now equals 0

`+=` Adds the value of the right operand to the left operand and assigns the value to the variable.
Ex:	`1 += 3`	//	`4`

`-=` Subtracts the value of the right operand from the value on the left and assigns the new value.
Ex:	`5 -=3` // `2`

`*=` Multiplies the value of the right operand by the value of the left and assigns the new value.	
Ex:	`2 *= 3` // `6`

`/=` Divides the value of the right operand by the value on the left and assigns the new value.
Ex:	`10 /= 5` // `2`

Built-In Constants

Undefined

Assigned to a variable or argument when no value has been defined.

var X; if (x === undefined) { do something };

###NaN

Stands for Not a Number

`var x = “one”` 
`x * 3` 
`NaN`

###Infinity

Value representing numerical infinity.

2 / 0 // Infinity

##Others

Functions

Functions are a form of control flow used in computer programs. They are code that executes more code within the {}.

function keyword

The function keyword is used to define a function with parentheses and curly braces:

// This is a Function Definition for `whatever`...
function whatever ( /* arguments go here */ ) {
  // body of function goes here
}

Once a function has been defined, it can be invoked by whatever()

###typeof

typeof is an operator followed by only one operand. It returns the type of the operand.

typeof "Hello" // "string"