Get the first class name (index 0) of a <div> element:
var x = document.getElementById("myDIV").classList.item(0);
Click the button to display the class name of the first class (index 0) of div.
<!DOCTYPE html> <html> <head> <style> .mystyle {//from w w w .ja v a2 s . c o m width: 500px; height: 50px; } .anotherClass { background-color: lightblue; } .thirdClass { text-align: center; font-size: 25px; color: black; margin-bottom: 10px; } </style> </head> <body> <div id="myDIV" class="mystyle anotherClass thirdClass"> I am a DIV element with three classes </div> <button onclick="myFunction()">Test</button> <p id="demo"></p> <script> function myFunction() { var x = document.getElementById("myDIV").classList.item(0); document.getElementById("demo").innerHTML = x; } </script> </body> </html>