String length

The length method is used to check the length of the string

const str = "Hello";
console.log(str.length); 
//output will be 5

charAt() & charCodeAt()

charAt()Returns the character at the specified index.
charCodeAt() Returns the Unicode value of the character at the specified index.

const str = "Hello";
console.log(str.charAt(0));

const str = "Hello";
console.log(str.charCodeAt(0));

codepointat()

Returns the Unicode code point of the character at the specified index.

const str = "Hello";
console.log(str.codePointAt(0));
 // 72 (Unicode code point of "H")

Concatenation & at()

Concatenates two or more strings.
Returns the character at the specified index, similar to charAt(). Supports negative indices.

const str1 = "Hello";
const str2 = " World";
console.log(str1.concat(str2));                         
const str = "Hello";
console.log(str.at(0)); // "H"

String []

Returns the character at the specified index, similar to charAt(). String[] not used for negative indexes.

cconst str = "Hello";
console.log(str[0]); // "H"

Slice & substring

slice() extracts a part of a string and returns the extracted part in a new string.
substring() is similar to slice().
The difference is that start and end values less than 0 are treated as 0 in substring().

const str = "Hello World";
console.log(str.slice(6)); // "World"
console.log(str.slice(0, 5)); // "Hello"
const str = "Hello World";
console.log(str.substring(2, 6));

toUpperCase() & toLowerCase()

toUpperCase() Converts the string to uppercase.
toLowerCase() Converts the string to lowercase.

const str = "hello";
console.log(str.toUpperCase());
const str = "HELLO";
console.log(str.toLowerCase());

isWellFormed() & toWellFormed()

isWellFormed() This method checks if a string is well-formed according to specific rules.
This method takes a string and returns a well-formed version of it. It may replace or remove characters that are not well-formed according to specific rules.

const str = "Hello";
console.log(str.isWellFormed());
const str = "\uD800"; // lone surrogate
console.log(str.toWellFormed());
 // "\uFFFD" (replacement character)

trim(),trimStart() & trimEnd()

trim() Removes whitespace from both ends.
trimStart() Removes whitespace from the start.
trimEnd() Removes whitespace from the end.

const str = "   Hello   ";
console.log(str.trim()); // "Hello"
const str = "   Hello   ";
console.log(str.trimStart()); // "Hello   "
const str = "   Hello   ";
console.log(str.trimEnd()); /

padStart() & padEnd()

padStart() Pads the string with a specified string from the start.
padEnd() Pads the string with a specified string from the end.

const str = "Hello";
console.log(str.padStart(8, "*")); // "***Hello"
const str = "Hello";
console.log(str.padEnd(8, "*")); // "Hello***"

repeat() & replace()

repeat() Repeats the string much time you want.
The replace() method replaces a specified value with another value in a string:

const str = "Hello";
console.log(str.repeat(3));
let text = "Please visit";
let newText=text.replace("visit", "he")

replaceAll() & split()

replaceAll() are used to replace all of the things that were selected
split() method is used to split a string into an array based on a given separator (like space, comma, or any character).

const str = "Hello World, Hello!";
console.log(str.replaceAll("Hello", "Hi")); // "Hi World, Hi!"
const str = "Hello,World,!";
console.log(str.split(",,,")); // ["Hello",,, "World",,, "!"]