How to find the width of hidden text on the webpage?

[pcman]

So I am trying to add this tooltip, which gets resized based on the width of the text it contains. Tooltip is a div and it has another div containing the text.\[code\]<div><div> tooltip text </div></div>\[/code\]I assign text to it using javascript as mytooltiptext.innerHTML=sometext. The tooltip is hidden with display set to none, and becomes visible on mouse hover. I am trying to set its width before it even becomes visible based on the width of the text/text containing div. But when I try to get the clientWidth or scrollWidth of the text containing div, it comes out as zero. My understanding is that it is happening due to the element being hidden. I tried setting its display to block and visibility to hidden and then tried to get the requisite values, but to no avail. Is there a way to get the width of hidden text without making it visible first?