Notes

JAVA SCRIPT

STRING

string are immutable language- here immutable means if you change any thing in the string that means its make a new string

let str=" aryan verma"

METHOD IN STRING
there are some method in string in string we use as per our requirement

let str="aryan verma";


1.TRIM();

console.log(str.trim());

trim()- the function trim() is use for remove a space in the string .
replace();


2.SLICE();

slice()-the means of slice is katna its make other str of the cutting element

str.slice(2,5)= ans is [yan]
str.slice(2)= ans is [yan verma]


3.TOUPPERCASE();

.4TOLOWERCASE();

.5TOREPLACE();

6.INDEXOF();



ARRAY DATA STRUCTURE

let array= [" aryan", " verma" ];
let array= [" aryan", " verma" , 1,2 ] ; this only happen in java script ( take different typr of data type);

Array are muttable- here muttable means if you change anythink in the array then its change in the main array

4 function use in array

1. POP(); - remove from last
2.PUSH(); - add in last
3.UNSHIFT(); - add in first space
4. SHIFT(); - remove from first

SOME ARRAY METHOD

1. Array.sort(); - this method sort the array in string ( also in case of number it sort in string form);
2. Array.indexOf( " name" ); - remains that o is capital
3. Array.includes( " name"); - answer in true or false
4.Array.slice() - first the meaning of slice is ( katna in hindi) .

slice(2) - it cover all the element after two
slice(2,3)- it cover 2 only
slice(-2)- remove two element at last

5. Array.concat(array2); - add two array
6. Array.reverse();
7. Array.splice()- its all work same like the slice but its change in the main array but slice does not interfare with your orginal array.
splice(1,2) -select first index element and remove 2 element;
splice(1,2," heelo", " hi")- select first index element and remove 2 element and add heelo and hi;

these are different for slice();



Array reference

if you make an array then remeber you store the address of the element in the aray.
eg- let arr1=[1,2,3]
let arr2=[1,2,3]

arr1==arr2; - false
arr1===arr2 - false

let arr1=arr2;

arr1==arr2; - true
arr1===arr2; -true


NESTED ARRAY

let arr1=[ [ 2,3] , [ 4,5] ]

two array in a single array.



OBJECT LITERALS:-

USED TO STORE KEY COLLECTION

property -(key,value);

SYNTAX:-

let student={

name:" aryan",
age:20,
marks:"80"
};
or
let student2={"aryan",20,80};

or

let student3={
name:"aryan";
color: ["blue", "red"];
};

eg:-

const post={
username:"@aryan";
contenet: "this is my #firstpost";
likes:150,
tags:["@aryan"," @bluearmy"]
};

GET VALUE
IF YOU WANT TO GET VALUE

then we call :-
post["likes"] here like is not a key
or
post.content;
post.tags;

**:-here we also change information that store in these object
**:- also we more object in a single one object.



MATH OBJECT

MATHS.PI();
MATHS,ABS();
MATHS.RANDOM();
MATHS.CEIL();
MATHS.FLOOR();

these are the important math function that we use in our regular js.



FUNCTION IN JAVA SCRIPT

function name(){
console.log(" hello");

}


FUNCTION WITH ARGUMENTS

FUNCTION ARGUMNEMT IN JS ARE DIFFERENT AS COMPARE TO JAVA
function name(a1,a2){
console.log(a1,a2);
}

CALLING OF A FUNCTION
name(aryan, verma); // define our function