Detect sub-pixel word- and letter-spacing.

subpixel-word-spacing-detect.js

var subpixelWordSpacing = false;

if (document.defaultView && document.defaultView.getComputedStyle) {
	// Store the original word spacing on the document element
	var originalWordSpacing = document.defaultView.getComputedStyle(document.documentElement, null).wordSpacing;
	
	// Set the word-spacing to half a pixel
	document.documentElement.style.wordSpacing = '0.5px';
	
	// This will return either 0px or 1px if sub-pixel word-spacing is not supported, otherwise
	// it will return 0.5px.
	subpixelWordSpacing = document.defaultView.getComputedStyle(document.documentElement, null).wordSpacing === '0.5px';
	
	// Restore the original word-spacing
	document.documentElement.style.wordSpacing = originalWordSpacing;
}

Wouldn't this make more sense to start off with subpixelWordSpacing set as false? Checking the document.defaultView exists may be false and then leave subpixelWordSpacing as true in cases where the browser doesn't support it.

My thoughts exactly. And maybe store the original value so you can restore it properly instead of resetting to 0.

@stephen-uac, @CrocoDillon: excellent feedback! I only used this as a quick test to see if sub-pixel word spacing was supported or not. The changes you suggested make it a lot more robust. I've updated the Gist.