A JavaScript String is a sequence of characters, typically used to represent text.

• In JavaScript, there is no character type (Similar to Python and different from C, C++ and Java), so a single character string is used when we need a character.
• Like Java and Python, strings in JavaScript are immutable.

Create using Literals - Recommended

We can either use a single quote or a double quote to create a string. We can use either of the two, but it is recommended to be consistent with your choice throughout your code.

// Using Single Quote
let s1 = 'abcd';
console.log(s1);

// Using Double Quote
let s2 = "abcd";
console.log(s2);

Create using Constructor

The new String() constructor creates a string object instead of a primitive string. It is generally not recommended because it can cause unexpected behavior in comparisons

let s = new String('abcd');
console.log(s);

Template Literals (String Interpolation)

You can create strings using Template Literals. Template literals allow you to embed expressions within backticks (`) for dynamic string creation, making it more readable and versatile.

let s1 = 'gfg';
let s2 = `You are learning from ${s1}`;

console.log(s2);

Empty String

You can create an empty string by assigning either single or double quotes with no characters in between.

let s1 = '';
let s2 = "";

console.log(s1);
console.log(s2);

Since the strings are empty, console.log will print two blank lines.

Multiline Strings (ES6 and later)

You can create a multiline string using backticks (``) with template literals. The backticks allows you to span the string across multiple lines, preserving the line breaks within the string.

let s = `
    This is a
    multiline
    string`;

console.log(s);

Basic Operations on JavaScript Strings

1. Finding the length of a String

You can find the length of a string using the length property.

let s = 'JavaScript';
let len = s.length;

console.log("String Length: " + len);

2. String Concatenation

You can combine two or more strings using + Operator.

let s1 = 'Java';
let s2 = 'Script';
let res = s1 + s2;

console.log("Concatenated String: " + res);

3. Escape Characters

We can use escape characters in string to add single quotes, dual quotes, and backslash.

\' - Inserts a single quote
\" - Inserts a double quote 
\\ - Inserts a backslash

const s1 = "\'GfG\' is a learning portal";
const s2 = "\"GfG\" is a learning portal";
const s3 = "\\GfG\\ is a learning portal";

console.log(s1);
console.log(s2);
console.log(s3);

4. Breaking Long Strings

Using a backslash (\) to break a long string is not recommended, as it is not supported in strict mode. Instead, use template literals or string concatenation.

const s = "'GeeksforGeeks' is \
a learning portal";

console.log(s);

Note: This method might not be supported on all browsers. A better way to break a string is by using the string addition.

const s = "'GeeksforGeeks' is a"
    + " learning portal";

console.log(s);

5. Find Substring of a String

We can extract a portion of a string using the substring() method.

let s1 = 'JavaScript Tutorial';
let s2 = s1.substring(0, 10);

console.log(s2);

6. Convert String to Uppercase and Lowercase

Convert a string to uppercase and lowercase using toUpperCase() and toLowerCase() methods.

let s = 'JavaScript';
let uCase = s.toUpperCase();
let lCase = s.toLowerCase();

console.log(uCase);
console.log(lCase);

7. String Search in JavaScript

Find the first index of a substring within a string using indexOf() method.

let s1 = 'def abc abc';
let i = s1.indexOf('abc');

console.log(i);

8. String Replace in JavaScript

Replace occurrences of a substring using the replace() method. By default, replace() only replaces the first occurrence. To replace all occurrences, use a regular expression with the g flag.

let s1 = 'Learn HTML at GfG and HTML is useful';
let s2 = s1.replace(/HTML/g, 'JavaScript');

console.log(s2);

9. Trimming Whitespace from String

Remove leading and trailing whitespaces using trim() method.

let s1 = '    Learn JavaScript       ';
let s2 = s1.trim();

console.log(s2);

10. Access Characters from String

Access individual characters in a string using bracket notation and charAt() method.

let s1 = 'Learn JavaScript';
let s2 = s1[6];
console.log(s2);

s2 = s1.charAt(6);
console.log(s2);

11. String Comparison in JavaScript

There are some inbuilt methods that can be used to compare strings such as the equality operator and another like localeCompare() method.

let s1 = "Ajay"
let s2 = new String("Ajay");

console.log(s1 == s2);  // true (type coercion)
console.log(s1 === s2); // false (strict comparison)
console.log(s1.localeCompare(s2)); // 0 (means they are equal lexicographically)

Note: The equality operator (==) may return true when comparing a string object with a primitive string due to type coercion. However, === (strict equality) returns false because objects and primitives are different types. The localeCompare() method compares strings lexicographically.

12. Passing JavaScript String as Objects

We can create a JavaScript string using the new keyword.

const str = new String("GeeksforGeeks");

console.log(str);

Are the strings created by the new keyword is same as normal strings

No, the string created by the new keyword is an object and is not the same as normal strings.

const str1 = new String("GeeksforGeeks");
const str2 = "GeeksforGeeks";

console.log(str1 == str2);
console.log(str1 === str2);

Also Check :

• Interesting Facts about JS Strings
• JS String Reference
• JS String Exercise