Question

How to set relative 50% 50% position using JS?

I tried:

document.getElementById("id").style.position = "relative 50% 50%";

but it don’t seems to work…

Answer 1

You have to set them individually.

I made a variable to point to the style object, because we are modifying more than one property and because with() { ... } is considered harmful.

Also, I set the 50% to both properties because of right to left assignment, and because assignment of this string to the two properties isn’t a problem (make sure you understand how this works, e.g. var a = b = [] will set a and b to the same Array object, often not desired).

var elementStyle = document.getElementById("id").style;

elementStyle.position = "relative";

elementStyle.top = elementStyle.left = "50%";

jsFiddle.