JavaScript String Methods Explained with Examples

Strings are everywhere in Javacript — Whether you are working with user input, API responses or formatting ouput. Thankfully javascript has a set of string methods to manipulate the text easily.

String is a datatype in programming languages which can be used to store text rather than numbers.A string sequence of characters can contain letters,numbers,spaces,symbols.It must be enclose within quotes to recognize it as a string.

In JavaScript we can create strings in two ways By using

▪️String Literal: let s1=”name”

▪️ String Object : let s2=new String(“hellooo”)

String Methods

The first thing we have to know about these string methods are ,They don’t modify the original string.

𝒍𝒆𝒏𝒈𝒕𝒉

length property returns the length of the string

let text="abcdefghijklmno"
//finding string length
let length=text.length
console.log(length)

𝒔𝒍𝒊𝒄𝒆( )

slice ( ) method extracts a part from the string and returns the extracted part as a new string

It takes two parameters :start position(included) and end position(excluded),if the end position is not mentioned then it will slice out the rest of the string.

If a parameter is negative ,the position is countered from the end of the string

let text="abcdefghijklmno"
//extracting a part of the string

//mentioned start and end
let partofText=text.slice(2,7)
console.log(partofText)

//mentioned only start
partofText=text.slice(6,)
console.log(partofText)

//negative parameter
partofText=text.slice(-9,-5)
console.log(partofText)

𝒔𝒖𝒃𝒔𝒕𝒓𝒊𝒏𝒈( )

It is similar to slice ( ),which can extracts a part of string

But The difference ,if the start and end values are given as negative they are treated as 0 and if we gave start is higher index and end as a lower index number,then the substring ( ) will return the string from the lower index till the higher index.

let text="abcdefghijklmno"
//extracting a part of the string

//mentioned start and end
let partofText=text.substring(2,7)
console.log(partofText)

//mentioned only start
partofText=text.substring(6,)
console.log(partofText)

//negative parameter
partofText=text.substring(-9,5)
console.log(partofText)

//mentioning start and end
partofText=text.substring(10,5)
console.log(partofText)

𝒔𝒖𝒃𝒔𝒕𝒓( )

substr ( ) is also similar to slice ( )

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But the difference the first is same as in slice( ) which mentions the start index but the second parameter specifies the length of the extracted part

let text="abcdefghijklmno"
//extracting a part of the string

//mentioned start and end
let partofText=text.substr(2,5)
console.log(partofText)

//mentioned only start
partofText=text.substring(4,)
console.log(partofText)

𝒓𝒆𝒑𝒍𝒂𝒄𝒆( )

replace ( ) method replaces a specified value with another value in string.By default the replace method will replaces only first match ,to replace all the matches we can use replaceAll( ) ,it was introduced in 2021.

let text="abcdefghijklmno"

//replacing a part of the string
let newText=text.replace("abcd","ABCD")
console.log(newText)

𝒄𝒐𝒏𝒄𝒂𝒕( )

conact ( ) can be used to join two or more strings,this can be used of plus operator ,to join the strings

let text1="abcdefg"
let text2="hijklmno"
//concatinating
let text3=text1.concat(" ",+text2)

𝒕𝒐𝑼𝒑𝒑𝒆𝒓𝑪𝒂𝒔𝒆( ) 𝒂𝒏𝒅 𝒕𝒐𝑳𝒐𝒘𝒆𝒓𝑪𝒂𝒔𝒆( )

toUpperCase( ) used to convert the string into uppercase

toLowerCase( ) used to convert the string itno lowercase

let text1="abcdefg"
let text2="HIJKLMNO"
//converting Cases
let text1Upper=text1.toUpperCase();
let text2Lower=text2.toLowerCase();

console.log(text1Upper);
console.log(text2Lower);

𝒄𝒉𝒂𝒓𝑨𝒕( ), 𝒂𝒕 ( )

To know the character based on the given index in a string

charAt( ) takes positive numbers as parameters

at( ) can take negatives also and gives the character from the end of the list

let text1="abcdefg"

//finding the character at 2nd index
let char=text1.charAt(2)
let char=text1.charAt(-2)

let char=text1.at(2)
let char=text1.at(-2)

𝒔𝒑𝒍𝒊𝒕( )

A string can be converted to an array with the split ( ) method

If the separator is omitted, the returned array will contain the whole string in index [0]. If the separator is “”, the returned array will be an array of single characters:

let text1="abcdefg,hijkl"
//splitting the string based on the delimiter
let s1=text1.split(",");
let s2=text1.split();
let s3=text1.split("");
console.log(s1)
console.log(s2)
console.log(s3)

𝒊𝒏𝒅𝒆𝒙𝑶𝒇( )

To know the index of character in a string

let text1="abcdefghijkl"
//finding index of b
console.log(text1.indexOf('b'));