Strings in JavaScript

Strings in JavaScript

10 May 2024
Beginner
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19 min read
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Strings in JavaScript

Strings in JavaScript are a sequence of characters that may consist of letters, numbers, or symbols. It can be enclosed in either single quotes or double quotes. 

In this JavaScript tutorial, we'll discuss all the aspects of strings starting from declaration to various string methods. Consider enrolling in our JavaScript Programming Course to get a thorough practical understanding.

What is a String in JavaScript?

Strings represent text. A JavaScript string is a primitive data type used for storing texts. They are written inside quotes.

JavaScript String Example


const name = 'Welcome to ScholarHat';

Important Terminologies of a JavaScript String

  • String: It is a sequence of characters enclosed in single (‘ ‘) or double (” “) quotes.
  • Length: The number of characters in a string, obtained using the length property.
  • Index: It indicates the position of a character within a string, starting from 0.
  • Concatenation: The combination of two or more strings to create a new one.
  • Substring: It is a portion of a string, obtained by extracting characters between specified indices.

Read More: JavaScript Interview Questions and Answers

Creation of JavaScript Strings/Declaration of a String in JavaScript

There are various methods to create or declare a string in JavaScript

1. Using Single Quotes

In this, you can create a string by enclosing it within single quotes.

Syntax


let str = 'String with single quote';

Example


let str = 'Welcome to ScholarHat';   
console.log(str);
    

Output

Welcome to ScholarHat

2. Using Double Quotes

In this, enclose your text inside double quotes to declare a string.

Syntax


let str = 'String with double quotes';

Example


let str = "Welcome to ScholarHat";   
console.log(str);
    

Output

Welcome to ScholarHat

Remember: Single quotes and double quotes are practically the same and you can use either of them.

3. String Constructor

Here, a new keyword is used to create an instance of string.

Syntax


let str=new String("string literal");

Example


let str = new String('Welcome to ScholarHat');   
console.log(str);
    

Output

Welcome to ScholarHat

4. Using Template Literals (String Interpolation)

Templates are strings enclosed in backticks (`ScholarHat`). With template literals, you can embed expressions within backticks (`) for dynamic string creation. You can create multiline strings using this method.

Syntax


let str = 'Template Litral String';
let newStr = `String created using ${str}`;
or 
let str = `
    Multiline
    String`;

Example


let str = 'Welcome to ScholarHat'; 
let newStr = `String created using ${str}`; 
=
console.log(newStr);
    

Output

Welcome to ScholarHat

Example


let str = ` 
    Welcome to  
    this JavaScript tutorial
     of ScholarHat`; 

console.log(str);
    

Output

Welcome to  
this JavaScript tutorial
of ScholarHat

Fundamental Concepts of JavaScript Strings

  • JavaScript Strings are immutable

    The characters of a string cannot be changed in JavaScript once it is declared.

    Example

    
    let str = 'ScholarHat';
    str[0] = 's';
    console.log(str);
        

    Output

    ScholarHat
    

    You can't modify the string once created but you can assign a new string to the same variable.

    Example

    
    let str = 'ScholarHat';
    str = 'scholarhat';
    console.log(str);
        

    Output

    scholarhat
    
  • JavaScript is Case-Sensitive

    In JavaScript, the lowercase and uppercase letters are treated as different values.

    Example

    
    const str = 's';
    const str1 = 'S'
    console.log(str === str1);
        

    Output

    
    false
    
  • String Objects and normal strings are different in JavaScript

    In JavaScript, the string created by the new keyword is an object and is not the same as normal strings.

    Example

    
    const str1 = new String("Welcome to ScholarHat"); 
    const str2 = "Welcome to ScholarHat"; 
    
    console.log(typeof str1); 
    console.log(typeof str2); 
    
    console.log(str1 == str2); 
    console.log(str1 === str2);
        

    In the above code, as str1 is an object and str2 is a normal string, the "===" operator returns false.

    Output

    object
    string
    true
    false
    

Escape Characters

You can use the backslash escape character \ to include special characters in a string.

The following table describes the special characters you can use with \.

CodeOutput
\"include double quote
\\include backslash
\nnew line
\rcarriage return
\vvertical tab
\thorizontal tab
\bbackspace
\fform feed

String Manipulation

1. Access String Characters

This can be done in two ways:

  1. Using indexes

    A string is an array of characters. Hence, we can access its characters using specific indexes.

    Example

    
    let str = 'ScholarHat';
    console.log(str[2]);
        

    Output

    h
    
  2. Using charAt() method

    Example

    
    let str = 'ScholarHat';
    console.log(str.charAt(2));
        

    Output

    h
    

2. String Concatenation

This can be done using the + Operator.

Example


let str1 = 'Welcome to'; 
let str2 = 'ScholarHat'; 
let result = str1 + str2; 
console.log("Concatenated String: " + result);
    

Output

Concatenated String: Welcome to ScholarHat

3. String Comparison in JavaScript

This can be done in two ways:

  1. Using equality operator

    It returns the result in boolean values.

    Example

    
    let str1 = "ScholarHat"; 
    let str2 = new String("ScholarHat"); 
      
    console.log(str1 == str2);
        

    Output

    true
    
  2. Using localeCompare() method

    It returns the result in ASCII values.

    Example

    
    let str1 = "ScholarHat"; 
    let str2 = new String("ScholarHat"); 
      
    console.log(str1.localeCompare(str2));
        

    Output

    0
    

4. JavaScript String Length

This is done using the built-in length property.

Example


let str = 'ScholarHat'; 
let len = str.length; 
console.log("String Length: " + len);
    

Output

String Length: 10

JavaScript String Methods

The table below describes the commonly used JavaScript String methods

MethodDescription
charAt(index)returns the character at the specified index
concat() joins two or more strings
replace() replaces a string with another string
split() converts the string to an array of strings
substr(start, length) returns a part of a string
substring(start,end) returns a part of a string
slice(start, end) returns a part of a string
toLowerCase() returns the passed string in lower case
toUpperCase() returns the passed string in the upper case
trim()removes whitespace from the strings
includes()searches for a string and returns a boolean value
search()searches for a string and returns a position of a match
trimStart()removes whitespace from the beginning of a string
trimEnd()removes white space from the end of a string
padStart()pad a string with another string until it reaches the given length
padEnd()pad a string with another string until it reaches the given length
valueOf()Return the value of the given string
match()Search a string for a match against any regular expression
indexOf()Finds the index of the first occurrence of the argument string in the given string

Example to Demonstrate the Working of JavaScript String Methods


let text1 = 'Welcome to';
let text2 = 'ScholarHat';
let text3 = '     JavaScript    ';

// concatenating two strings
const result1 = text1.concat(' ', text2);
console.log(result1); 

// converting the text to uppercase
const result2 = text1.toUpperCase();
console.log(result2); 

// converting the text to uppercase
const lwres = text1.toLowerCase();
console.log(lwres);

// gives the substring of a string
let part = text1.substring(6, 10);
console.log(part);

// removing whitespace from the string
const result3 = text3.trim();
console.log(result3); 

//replaces a part of the given string
let rep = text2.replace("ScholarHat", "DotNetTricks");
console.log(rep)

// converting the string to an array
const result4 = text1.split();
console.log(result4); 

// slicing the string
const result5= text1.slice(1, 3);
console.log(result5); 

Output

Welcome to ScholarHat
WELCOME TO
welcome to
e to
JavaScript
DotNetTricks
[ 'Welcome to' ]
el   

JavaScript String() Function

The String() function in JavaScript converts various data types to strings.

Example of String() Function in JavaScript


const a = 125; // number
const b = true; // boolean

//converting to string
const result1 = String(a);
const result2 = String(b);

console.log(result1);
console.log(result2);

In the above program, the String() function converts the number and boolean data type variables into strings.

Output

125
true
Summary

In the above blog, we saw with illustrations a complete picture of Strings in JavaScript. You won't face any difficulty while going through the article. For a practical understanding, consider our JavaScript Programming Course.

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About Author
Sakshi Dhameja (Author and Mentor)

She is passionate about different technologies like JavaScript, React, HTML, CSS, Node.js etc. and likes to share knowledge with the developer community. She holds strong learning skills in keeping herself updated with the changing technologies in her area as well as other technologies like Core Java, Python and Cloud.

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