Use of the JavaScript substr () string truncation Function

Substr definition and usage
The substr () method extracts a specified number of characters starting with the start subscript from a string.

Syntax
StringObject. substr (start, length)

Parameters	Description
Start	Required. The starting subscript of the substring to be extracted. It must be a numerical value. If it is a negative number, this parameter declares the position starting from the end of the string. That is to say,-1 refers to the last character in the string,-2 refers to the second to last character, and so on.
Length	Optional. The number of characters in the substring. It must be a numerical value. If this parameter is omitted, the string from the start position of the stringObject to the end is returned.

Description
If the length is 0 or negative, an empty string is returned. If this parameter is not specified, the substring will continue to the end of stringvar.

Example
The following example demonstrates the substr method usage.

The first truncates the first character of the string.


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Result: j


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It refers to the truncation of a string starting from 12th characters and being 5 characters in length.

In this example, we will use substr () to extract some characters from the string:

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Output:

Lo world!

Example 2

In this example, we will use substr () to extract some characters from the string:

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Output:

Lo worl