Javascript - String substr() Method

The substr() method returns parts of a string, beginning at the specified position, and returns the specified number of characters.

Description

The substr() method returns parts of a string, beginning at the specified position, and returns the specified number of characters.

To extract characters from the end of the string, use a negative start number.

The substr() method does not change the original string.

Syntax

string.substr(start,length)

Parameter Values

Parameter Require Description
start Required. The position to start the extraction. First character is at index 0. If start is positive and greater than, or equal, to the length of the string, substr() returns an empty string.If start is negative, substr() uses it as a character index from the end of the string. If start is negative or larger than the length of the string, start is set to 0
lengthOptional.The number of characters to extract. If omitted, it extracts the rest of the string

Return

A new String, containing the extracted part of the text. If length is 0 or negative, an empty string is returned

Example

Extract parts of a string:

Demo

//extract parts of the string.
var str = "Hello world!";
var res = str.substr(1, 4);
console.log(res);//from  w  ww .j  a  va  2s.  c o  m

//Begin the extraction at position 2, and extract the rest of the string:
var str = "Hello world!";
var res = str.substr(2);
console.log(res);

//Extract only the first character:
var str = "Hello world!";
var res = str.substr(0, 1);
console.log(res);

//Extract only the last character:
var str = "Hello world!";
var res = str.substr(11, 1);
console.log(res);

Result