JS substr - Javascript

Introduction

substr() is a string method in Javascript which extracts a specific number of characters from a string, starting from a specified position.

Syntax

string.substr(start, length)

• start - Required. The position where to start the extraction. First character is at index 0. If negative, it is treated as strLength + start where strLength is the length of the string.
• length - Optional. The number of characters to extract. If omitted, it extracts the whole string from the start position.

Example

var str = "Hello world!";
var res = str.substr(1, 4);
console.log(res); // ello

Explanation

In the example above, substr() method extracts 4 characters from str starting at index 1, which is "ello".

Additional Information

• substr() method does not change the original string. It returns a new string.
• If start is greater than or equal to the length of the string, an empty string is returned.
• If length is negative, it is treated as 0.
• substr() method is not supported in IE 7 and earlier versions.

Conclusion

substr() method is a useful string method in Javascript for extracting a portion of a string. It is simple and easy to use, and can be used in many different applications.