String substr()

substr() returns a substring and accepts either one or two arguments.

The first argument is the starting position. The second argument tells where to stop in term of the number of characters to return. If the second argument is omitted, it is default to the ending of the string.

substr() does not alter the value of the string itself.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
        var stringValue = "hello world"; 
        
        document.writeln(stringValue.substr(3)); //"lo world" 
        document.writeln(stringValue.substr(3, 7)); //"lo worl" 
            

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

A negative first argument does the sub string from the end. A negative second number is converted to 0.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
        var stringValue = "hello world"; 
        
        document.writeln(stringValue.substr(-3)); //"rld" 
        document.writeln(stringValue.substr(3, -4)); //"" (empty string) 
            

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo