The substr () method in JavaScript uses a detailed knowledge of the basics

This method returns the character in a string at the specified position by the specified number of characters.
Grammar

String.substr (start[, length]);

The following are the details of the parameters:

• Start: Extract character at position (a length of 0 and integer less than string)
• Length: The number of characters to use to extract

Note: If start is a negative number, SUBSTR uses it as an index from the end character of the string
return Value:

• The Substr method returns a new substring based on the given argument

Example:

This will produce the following results:

(1,2): pp
( -2,2): Ap
(1): Pples are round, and apples are.
( -20, 2): Ap
(2): D