Javascript Day 2 ,3 and 4 
Tags: javascript, programming, webdev
Published: 2022-01-24 07:50:16

sharing the knowledge of Arrays and Strings in Javascript:

**Arrays.js **
// 📌array decalration in js

let array=[1,2,3,4,5];
console.log(array);


//📌length of array
console.log(array.length);


//📌while loop
let i=0;
while(i<array.length)
{
    console.log("The element at ",i,"is->",array[i]);
    i++;
}


//📌 In javascript we can add any data type in array , suppose we have a array of 1,2,3,4,5 amd we want to add "hello"
// which is a string , so we can add that in it 



//📌📌push (adding to back), unshift(adding to front)
array.push("last value");
console.log(array);

//👉ans --> [ 1, 2, 3, 4, 5, 'last value' ]

array.unshift("first value");
console.log(array);

//👉 ans -->[ 'first value', 1, 2, 3, 4, 5, 'last value' ]

//📌📌pop(removing from last) ,shift(removing from front )

array.pop();
console.log(array);

//👉 ans -->[ 'first value', 1, 2, 3, 4, 5 ]

array.shift();
console.log(array);
// 👉ans -->[ 1, 2, 3, 4, 5 ]


// 📌📌indexof ,contains[see yourslef]


//📌📌slice(staring index,ending index)--> you can relate to as substring , 
let partofarray=array.slice(2,4);
console.log(partofarray);


// ans -->[ 3, 4 ] i.e isne last wale index se pehle ka maal bheja hai 

let partofarray2=array.slice(2);
console.log(partofarray2);


// ans-->[ 3, 4, 5 ] i.e usne 2 se lekar saare end tak de diye

// 📌📌splice (staring,ending) --> it deletes from starting to ending index (it changes the array and not gives the copy array wih changes)

array.splice(2,3);
console.log(array);

 //ans -->[ 1, 2 ]  i.e it deletes from 2nd index and deletes 3 values from 2nd index (you can consider 3 as count and not the index)

//indexof()[basically gives the index of any element ] and contains()[it tells whether the element is present or not ] 


**Strings**
// 📌STRINGS

//👉 i.e string can be declared in single and double quotes unlike java 
let singlequote ='single quote ki string';
let doublequote ="double quote ki string";

console.log(singlequote);
console.log(doublequote);


//📌charAt
let char =singlequote.charAt(3);
console.log(char);


// ans-->g

//📌charCodeAt
// (basically it gives ascii value of the charAt )

let ascii=singlequote.charCodeAt(3);
console.log(ascii);

// ans-->103 (ascii value of g)

//📌substring
// (it gives substring as java )
let substr =singlequote.substring(2,8);
console.log(substr);

// ans-->ngle q



//📌split 
// (it acts like split in java (stringBuilder) but here it gives array of strings as output)


let arrstr=singlequote.split("i");
console.log(arrstr);
// ans-->[ 's', 'ngle quote k', ' str', 'ng' ]


let nospace =singlequote.split("");
console.log(nospace);
// ans-->[
//     's', 'i', 'n', 'g', 'l',
//     'e', ' ', 'q', 'u', 'o',
//     't', 'e', ' ', 'k', 'i',
//     ' ', 's', 't', 'r', 'i',
//     'n', 'g'
//   ]

//📌 join 
// (int arrstr1 we have splitted on the basis of " "(space) and after that we have joined on the basis of $ )
let arrstr1=singlequote.split(" ");
console.log(arrstr1);
let str=arrstr1.join("$")
console.log(str);

// ans-->[ 'single', 'quote', 'ki', 'string' ]
// single$quote$ki$string

//📌trim
// (basically it removes white spaces from front and end )

let ans ='  hello my name is pushan    ';
console.log(ans.trim());


// ans-->hello my name is pushan
// (you can see that ans has so many white spaces infront and at back , so trim removes it )