Improved version of JavaScript fix for the iOS viewport scaling bug. See http://www.blog.highub.com/mobile-2/a-fix-for-iphone-viewport-scale-bug/

ios-viewport-scaling-bug-fix-original.js

// Original code from http://www.blog.highub.com/mobile-2/a-fix-for-iphone-viewport-scale-bug/

var metas = document.getElementsByTagName('meta');
var i;
if (navigator.userAgent.match(/iPhone/i)) {
	for (i=0; i<metas.length; i++) {
		if (metas[i].name == "viewport") {
			metas[i].content = "width=device-width, minimum-scale=1.0, maximum-scale=1.0";
		}
	}
	document.getElementsByTagName('body')[0].addEventListener("gesturestart", gestureStart, false);
}
function gestureStart() {
	for (i=0; i<metas.length; i++) {
		if (metas[i].name == "viewport") {
			metas[i].content = "width=device-width, minimum-scale=0.25, maximum-scale=1.6";
		}
	}
}

ios-viewport-scaling-bug-fix.js

// Rewritten version
// By @mathias, @cheeaun and @jdalton

(function(doc) {

	var addEvent = 'addEventListener',
	    type = 'gesturestart',
	    qsa = 'querySelectorAll',
	    scales = [1, 1],
	    meta = qsa in doc ? doc[qsa]('meta[name=viewport]') : [];

	function fix() {
		meta.content = 'width=device-width,minimum-scale=' + scales[0] + ',maximum-scale=' + scales[1];
		doc.removeEventListener(type, fix, true);
	}

	if ((meta = meta[meta.length - 1]) && addEvent in doc) {
		fix();
		scales = [.25, 1.6];
		doc[addEvent](type, fix, true);
	}

}(document));

}(document));? should be })(document);

@ericmuyser - you can write it either way. The latter is more common, but the former works as well.

You might want to update with additional meta params, for iOS 6+.

function fix() {
        meta.content = 'width=device-width, initial-scale=1.0, maximum-scale=' + scales[1] + ', user-scalable=no, minimum-scale=' + scales[0];
        doc.removeEventListener(type, fix, true);
    }

hmm, still seems to create problems for me....

Is this fix still applicable to iOS or has Apple solved this issue?

Is this fix still applicable to iOS or has Apple solved this issue?

I also want to know...

I tested this code and its working well. thanks for sharing.

I don't think this works any more (iOS 10+) due to Apple now ignoring the scale meta tags