Node.js substr() function

The substr() function is a string function of Node.js which is used to extract sub-string from the given string. 

Syntax:

string.substr(index, length)

Parameters: This function accepts two parameters as mentioned above and described below:

• index: This parameter holds the starting index of the specified sub-string.
• length: This parameter holds the length of the sub-string.

Return Value: The function returns the sub-string from the given string. 

The below programs demonstrate the working of substr() function: 

Example 1:

javascript

function findsubstr(str) {
    let substring = str.substr(11, 13);
    console.log(substring);
}
const str = "Welcome to GeeksforGeeks";

findsubstr(str);

Output:

GeeksforGeeks

Example 2:

javascript

function findsubstr(str, index, length) {
    let substring = str.substr(index, length);
    console.log(substring);
}

const str = "Welcome to GeeksforGeeks";
const index = 11, length = 13;

findsubstr(str, index, length);

Output:

GeeksforGeeks