JavaScript substr

The JavaScript substr string function is one of the String functions, which is used to extract the part of a string and return in a new string. The syntax of the JavaScript substr function to return sub string is:

String_Object.substr(Start, Length)

JavaScript substr function will accept two arguments. The first integer value is the index position where the extraction will start, and the second integer value is the length of the substring.

JavaScript substr Function Example

The following set of examples will help you understand the Js substr function, and here, we declared a Str1 variable.

The second statement will extract five characters from the original, starting at index position 2.

Next, We omitted the second argument. It means JavaScript substr function will start at index position two and ends when it reaches last.

Within the following two JavaScript statements (Str5 and Str6), we used Negative and Zero values as the second argument. As we said before, this will return an empty string

Next, we used negative indexing. The following Str7 statement starts extracting from -3 (index position of 3 from right to left) and ends at last position.

HINT: If you are using the Negative numbers as index, JavaScript will start looking for items from right to left (Here, -1 is the Last Item, -2 is Last but one etc).

<!DOCTYPE html>
    <title> SubStrJavaScript </title>
    <h1> JavaScriptSubStr </h1>
    var Str1 = "Tutorial Gateway";
    var Str2 = Str1.substr(2, 8);
    var Str3 = Str1.substr(0, 8);
    var Str4 = Str1.substr(2);
    var Str5 = Str1.substr(2, -3);
    var Str6 = Str1.substr(2, 0);
    var Str7 = Str1.substr(-3);
    var Str8 = Str1.substr(-3, 2);
    document.write(Str2 + "<br \>");
    document.write(Str3 + "<br \>");
    document.write(Str4 + "<br \>");
    document.write(Str5 + "<br \>");
    document.write(Str6 + "<br \>");
    document.write(Str7 + "<br \>");
    document.write(Str8 );
JavaScript SUBSTR Function