hasAttribute

 
<!DOCTYPE HTML> 
<html> 
    <head> 
        <title>Example</title> 
    </head> 
    <body> 
        <p id="textblock" class="Survey numbers"> 
            This is a test.              
        </p> 
        <pre id="results"></pre> 
        <script> 
            var elem = document.getElementById("textblock"); 
            document.writeln("lang attribute: " + elem.hasAttribute("lang")); 
            elem.setAttribute("lang", "en-US"); 
            document.writeln("Attr value is : " + elem.getAttribute("lang")); 
            elem.setAttribute("lang", "en-UK"); 
            document.writeln("Value is now: " + elem.getAttribute("lang")); 
        </script> 
    </body> 
</html>
Click to view the demo