In JavaScript Both of the functions are used to get the specified part of the string, But there is a slight difference between them. substr() and substring() are string methods used to extract parts of a string. The main difference is that substr() accepts a length parameter, while substring() accepts start and end indices.

JavaScript str.substr() Function

The str.substr() function returns the specified number of characters from the specified index from the given string.

Syntax:

str.substr(start, len);

Example: This example uses only one parameter for both functions and produces the same output. 

const str1 = "GeeksForGeeks";
const substrResult = str1.substr(7);
const substringResult = str1.substring(7);

console.log("Str.substr(7) =", substrResult);
console.log("Str.substring(7) =", substringResult);

Str.substr(7) = rGeeks
Str.substring(7) = rGeeks

JavaScript str.substring() Function

This function gets the characters from a string, between two specified indices, and returns the new string.

Syntax:

str.substring(start, end);

Example: This example uses the parameter (3, 7) for both functions and returns the output. 

const str1 = "GeeksForGeeks";
const substrResult = str1.substr(3, 7);
const substringResult = str1.substring(3, 7);

console.log("Str.substr(3, 7) =", substrResult);
console.log("Str.substring(3, 7) =", substringResult);

Str.substr(3, 7) = ksForGe
Str.substring(3, 7) = ksFo

Difference between substr() and substring()