JavaScript String substr() Method

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JavaScript String substr() Method

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Example

Extract parts of a string:

var str = "Hello world!";

var res = str.substr(1, 4);

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The result of res will be:

ello

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More "Try it Yourself" examples below.

Definition and Usage

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

Tip: To extract characters from the end of the string, use a negative start number (This does not work in IE 8 and earlier).

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

Browser Support

Method
substr()	Yes	Yes	Yes	Yes	Yes

Syntax

string.substr(start, length)

Parameter Values

Parameter	Description
start	Required. The position where 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
length	Optional. The number of characters to extract. If omitted, it extracts the rest of the string

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Technical Details

Return Value:	A new String, containing the extracted part of the text. If length is 0 or negative, an empty string is returned
JavaScript Version:	ECMAScript 1

More Examples

Example

Begin the extraction at position 2, and extract the rest of the string:

var str = "Hello world!";

var res = str.substr(2);

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The result of res will be:

llo world!

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Example

Extract only the first character:

var str = "Hello world!";

var res = str.substr(0, 1);

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The result of res will be:

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Example

Extract only the last character:

var str = "Hello world!";

var res = str.substr(11, 1);

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The result of res will be:

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Try it Yourself »

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