DEV Community

PUSHAN VERMA
PUSHAN VERMA

Posted on

1

Javascript Day 2 ,3 and 4

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 {
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 )

Image of Docusign

Bring your solution into Docusign. Reach over 1.6M customers.

Docusign is now extensible. Overcome challenges with disconnected products and inaccessible data by bringing your solutions into Docusign and publishing to 1.6M customers in the App Center.

Learn more

Top comments (0)

The best way to debug slow web pages cover image

The best way to debug slow web pages

Tools like Page Speed Insights and Google Lighthouse are great for providing advice for front end performance issues. But what these tools can’t do, is evaluate performance across your entire stack of distributed services and applications.

Watch video

Retry later