String substr()

In JavaScript, String.substr() method is used to find the substring of a string which is defined by a specific start index, and an optional length.

Syntax

str.substr(start)           #if no length, then till the end
str.substr(start, length)

where

• str is a string.
• start is a number.
• length is a number.

substr() method finds the substring of given length from the given start.

Examples

1. In the following program, we find the substring of a string value in name, where the substring is defined by a specific start index.

let name = 'abcdefghijklmn';
let output = name.substr(6);
console.log(output);

2. substr(start) with start as negative number. If we give a negative value for index, then the index is considered from end towards start.

let name = 'abcdefghijklmn';
let output = name.substr(-6);
console.log(output);

3. In the following program, we find the substring of a string value in name, where the substring is defined by a specific start index in the string, and for a specific length.

let name = 'abcdefghijklmn';
let output = name.substr(6, 5);
console.log(output);