How to Get the Actual Rendered Font When It's Not Defined in Css

How to get the actual rendered font when it's not defined in CSS?

I suggest this function:

function css( element, property ) {
    return window.getComputedStyle( element, null ).getPropertyValue( property );
}

Usage:

css( object, 'font-size' ) // returns '16px' for instance

Note: getComputedStyle doesn't work in IE8.

Live demo: http://jsfiddle.net/4mxzE/

console.log(
  getComputedStyle(document.getElementById('test'), null)
    .getPropertyValue('font')
)

#test {
  font-family: fantasy, cursive;
}

<div id="test">Lorem ipsum dolor sit font-face</div>

How to get the rendered font in JavaScript?

It is still not possible to access this information from Web-APIs.

There is an ongoing discussion in the Houdini group about including a font-metrics API, that is supposed to include something like that, but it's still not even proposed as a spec draft and there will be a lot of burden on the road.

What font(s) are being used? This is complicated because multiple fonts can be used per paragraph, per line, per word, and even per glyph. The fonts should be exposed in the form of handles with complete font information, and (for web fonts) a handle to the raw font data. dbaron & eae are going to own this area and propose an API.

Indeed, one could have one font for the glyph ̂ (U+0302), and another one for the glyph a (U+0061) which would make the combined glyph â would actually use two different fonts.

Current discussions seem to point to a Font interface available from document.measureElement and document.measureText methods. This interface would expose two properties: a DOMString name, and a number glyphsRendered.
However, once again these are still discussion and still not yet proposed as drafts, a lot of discussion is still to be made and I wouldn't hold my breath waiting for it to be implemented anywhere any time soon.

Now, there are hacks, like numerous other Q/A already told _{^{don't stick to the accepted answer there}}, implying looking at the size of the rendering for the simplest, and looking at the rendered pixels for the more advanced ones, but being hacks, they won't work in every cases.

For instance, I could have a custom font on my system that would render only some characters borrowed from a well-known font, no such hack would be able to tell if the browser did fallback to that font or the actual well-known one.

The only way to know for sure is to keep the control and use web-fonts.

How can I determine what font a browser is actually using to render some text?

Per Wilfred Hughes' answer, Firefox now supports this natively. This article has more details.

This answer original referenced the "Font Finder" plugin, but only because it was from 4 years ago. The fact that old answers linger like this and the community cannot update them is one of the few remaining failures of Stack Overflow.

Why chrome shows rendered font which is different to computed font family?

Same as any other browser: if it can't find the first font, it tries the next, and so on and so on until it runs out of rules. If no fonts match, then the font is inherited from the parent element, all the way up to the document level, where it'll just pick the browser's default font.

In this case, things are a bit weird, because the order you're showing is "a real font" followed by "a generic CSS class that always resolves, but without any guarantee as to which font that will be, just that it'll be a sans-serif font", followed by the real font "futura".

So Chrome will try museo, won't find it, sees the generic "sans-serif" and just picks a known sans-serif font for you. Usually that's something like Arial or Helvetica, but the CSS spec doesn't say anything about which font it has to be, specifically. It just needs to be a sans-serif font.

The weird part here is that the ordering you chose means that the "futura" at the end will never be checked. The browser will always find a suitable font once it hits serif, sans-serif, cursive, fantasy, or monospace

How to Get the Actual Rendered Font When It's Not Defined in Css