Lecture 4

Table of content.

1.String

2.Number

What is Methods in Js ?

Methodho in funksiahoi taiore meboshad ki mo onhoro istifoda mebarem va onho kori moro oson mekunand A method is a block of code which only runs when it is called.You can pass data, known as parameters, into a method.Methods are used to perform certain actions, and they arealso known as functions.

What is String in Js?

String dar Js in iak namud typeOf ast va ba guruhi primitive dokhil meshavad va hamchunin methodhoi sting niz hast

Creating String in Js?

1."Doube Quotes"

"hello"

2."single Qoutes"

'hello

3."Backticks"

`Hello ${hi}`

Methods in Js?

1.charAt() : - The charAt() method returns the character at a specified index (position) in a string.

/// js
let str = "Hello"
console.log(str.charAt(1))

/// output : ---> o

2. at() : - This method allows for positive and negative integers. Negative integers count back from the last string character.

/// js
let str = "Hello"
console.log(str.at(-1))

/// output : ---> o

3. concat() : - The concat() method joins two or more strings, does not change the existing strings.

/// js
let str = "Hello"
let str2 = "Bilol
console.log(str.concat(" ",str2)))

/// output : ---> Hello Bilol

4.replace() : - The replace() method searches a string for a value or a regular expression.

/// js
let str = "Hello Ahmad"
let str2 = "Bilol"
console.log(str.raplace("Ahmad",str2)))

/// output : ---> Hello Bilol

5.replaceAll() : - The replaceAll() method returns a new string with all matches of a pattern replaced by a replacement.

// js
let str = "Hello Ahmad and Ahmad and Ahmad"
let str2 = "Bilol"
console.log(str.raplace("Ahmad",str2)))

/// output : ---> Hello Bilol and Bilol and Bilol

6.split() : - The split() method splits a string into an array of substrings. stringro megirad aray mekunad

// js
let str = "Hello Ahmad"
console.log(str.split()))
console.log(str.split("")))
console.log(str.split(" ")))

/// output : --->
[ "Hello Ahmad" ]
[ "H","e","l","l","o"," ","A","h","m","a","d",]
["Hello","Ahmad"]

7.substring() : - The substring() method extracts characters, between two indices (positions), from a string, and returns the substring

/// js
let str = "Hello Bilol"
console.log(str.substring(1,-1))

// output : --> ello Bilo

7.slice() : - slice misli substring kor mekunad ammo minusa kabul mekunad

/// js
let str = "Hello Bilol"
console.log(str.slice(-5))

// output : --> Bilol

toLowerCase() : - harfhor ba khurd tabdil medihad

/// js
let str = "hello
console.log(str.toLowerCase())
// output  : -- > HELLO 

toUpperCase() : - harfhor ba kalon tabdil medihad

/// js
let str = "HELLO"
console.log(str.toUpperCase())
// output  : -- > hello 

trim() : - mathode hast ki az du taraf probelhoi ziodatira megirad

/// js
let str = "    hello    "
console.log(str.totrim())
// output  : -- > hello 

includes() : - mesangad ki hast io nest

/// js
let str = "hello Bilol"
console.log(str.includes("Bilol"))
console.log(str.includes("Ahmad"))
// output  : -- > 
 true
 false 

toString() : - Raqamro ba string tabdil meihad

/// js
let str = 25
let res = str.toString()
console.log(typeOf(res))
// output  : -- > string 

indexOf() : - elementa indexsha nishon meta

/// js
let str = "hello
console.log(str.indexOf("l"))
// output  : -- > 2

repeat() : - takror nishon medihad

/// js
let str = "hello
console.log(str.repeat(3," "))
// output  : -- > hello hello hello 

Math.round() : - Az nim nigoh mekunad

/// js
let num1 = 6.6
let num2 = 6.3
console.log(Math.round(num1))
console.log(Math.round(num2))

/// output : --> 
7
6

Math.ceil() : - baland mekunad

/// js
let num1 = 6.6
let num2 = 6.3
console.log(Math.ceil(num1))
console.log(Math.ceil(num2))

/// output : --> 
7
7

Math.floor() : - past mekunad

/// js
let num1 = 6.6
let num2 = 6.3
console.log(Math.floor(num1))
console.log(Math.floor(num2))

/// output : --> 
6
6

Math.max() : - kalontarin raqamro meiobad

/// js
let num1 = (1,2,3,4,5,6)
console.log(Math.max(num1))

/// output : --> 
6

Math.min() : - khurdtarinro raqamro meiobad

/// js
let num1 = (1,2,3,4,5,6)
console.log(Math.min(num1))

/// output : --> 
1

Math.pow() : - ba daraja mebardorad

/// js
let num1 = 2
console.log(Math.pow(num1,5))

/// output : --> 
32

Math.sqrt() : - resharo neiobad

/// js
let num1 = 64
console.log(Math.sqrt(num1))

/// output : --> 
8

Math.abc() : - minusaro ba pilusa tabdil medihhad ammo pilusaro ba minusa tabdil namedihad

/// js
let num1 = -12
console.log(Math.abc(num1))

/// output : --> 
12

Math.random() : - kalontarin raqamro meiobad

/// js
let num1 = 10
console.log(Math.floor(Math.random(num1)*10))

/// output : --> 
6 , 10 , 4 , 7

isNaN() : - mesanjad ki raqam hast io ne

/// js
let num1 = 2+"2a"
let num2 = 10
console.log(isNaN(num1))
console.log(isNaN(num2))

/// output : --> 
true
false