Javascript Get Style And Increment

I'm trying to make a slider that changes the margin-left attribute in the external css onclick. So I need to get the attribute and then set the new attribute. here is my code: <

Solution 1:

In Javascript, the . operator does not concatenate strings.

Use the + operator instead:

document.getElementById(divName).style.marginLeft = y + 'px';

You also probably need to pass marginLeft as a string, not a name (unless there is a variable in scope that is named marginLeft and set to "marginLeft"):

var y = x.currentStyle["marginLeft"];

And:

var y = document.defaultView.getComputedStyle(x, null).getPropertyValue("marginLeft");