Return the left margin of a <div> element:
alert(document.getElementById("myDiv").style.marginLeft);
<!DOCTYPE html> <html> <head> <style> #myDiv {//from www. j ava 2s .co m border: 1px solid #FF0000; } </style> </head> <body> <div id="myDiv" style="margin-left:5cm;">This is a div.</div> <br> <button type="button" onclick="myFunction()">Return left margin</button> <p id="demo"></p> <script> function myFunction() { document.getElementById("demo").innerHTML = document.getElementById("myDiv").style.marginLeft; } </script> </body> </html>