JavaScript substring method

In Javascript, string.substring() returns the part of a string that begins at the start index and ends at the end index.

Syntax

string.substring(startIndex, endIndex)

Example: Javascript substring

const str = 'substring example';
const sub1 = str.substring(0,3);
const sub2 = str.substring(0,5);
const sub3 = str.substring(0,10);

console.log(sub1); // sub
console.log(sub2); // subst
console.log(sub3); // substring

Example: Javascript substring to the end of the string

The following example uses the substring() to extract a substring from the index 10 to the end of the string.

const str = 'substring example';
const sub = str.substring(10);

console.log(sub); // example

Example: Javascript substring

Using indexOf(), you can find out where the @ character is. After this, the substring returns the domain that starts from the index of @ plus one upwards.

let email = 'example@gmail.com';
let sub = email.substring(email.indexOf('@') + 1);

console.log(sub); // gmail.com

Example: Javascript substring negative values

Indexes always begin with 0. If we consider an index to be negative, it will be treated as zero.

const str = 'substring example';
const sub = str.substring(-2,10);

console.log(sub); // substring

A comparison between substring vs slice in JavaScript

Negative values

Negative numbers are interpreted by slice() as counting from the end of the string when entered as arguments. It will consider a negative value as zero when using substring().

const str = 'substring example';
const sub1 = str.substring(-5);
const sub2 = str.slice(-5);

console.log(sub1); // substring example
console.log(sub2); // ample

Parameter Consistency

In substring, the first argument will be swapped with the second argument if the first argument is greater than the second. Whenever the first argument is greater than the second, slice() returns an empty string.

const str = 'substring example';
const sub1 = str.substring(10,0);
const sub2 = str.slice(10,0);
const sub3 = str.slice(0,10);

console.log(sub1); // substring
console.log(sub2); // 
console.log(sub3); // substring

Javascript substring remove last character

This will remove last element.

const str = 'hello world';
const result = str.substring(0, str.length - 1)

console.log(result); // hello worl

Get substring between two characters javascript

This will print all values between : and ;

const str = 'hello:world;'

const result = str.substring(
    str.indexOf(":") + 1, 
    str.lastIndexOf(";")
);

console.log(result); // world

Javascript substring after character

This will print all values after :

const str = 'one:two'

const result = str.substring(
    str.indexOf(":") + 1, 
);

console.log(result); // two

Javascript substring before character

This will print all values before :

const str = 'one:two'

const result = str.substring(0, str.indexOf(":"));

console.log(result); // one

Javascript substring indexof

This will return the index of the first occurrence.

let str = "one two three four";
let result = str.indexOf("three");

console.log(result); // 8