I need an easy way to detect CSS3 media query supp

问题:

I need a quick and dirty way to detect media query support using jquery. I defined a function as follows:

function mediaQueriesEnabled () {
   var v = parseFloat($.browser.version);
   if ($.browser.msie) {
      if (v < 9)
         return (false);
   }
   return (true);
}

Can someone help me fix this up a bit? Looking at this page:

http://caniuse.com/css-mediaqueries

I realized that there are some complexities here. For example, when I test my version of safari, I get "534.57.2". I want to avoid installing modernizr for now, mainly because I'm in a crunch and I need to handle most situations in the short term. Any help is appreciated!

回答1:

You can create a stylesheet with a media query and see if it works.

In your HTML:

<style>@media all and (min-width:1px) {
    .mediatest {position:absolute}
}</style>

(Or you could dynamically create the stylesheet, but that's harder)

Then in your script:

var d = document.createElement('div');
d.className = "mediatest";
document.body.appendChild(d);
if( window.getComputedStyle && window.getComputedStyle(d).position == "absolute") {
    // supports media queries!
}
document.body.removeChild(d);

回答2:

EDIT: I'm no longer curating this answer as I feel that Niet's is much better (see chosen answer). It should still work, but may need some testing.

Cracking open Modernizr (which can test for media queries) we see it uses the window.matchMedia (MDN page) function. We can check in plain old vanilla JS to see if this function exists:

function mediaQueriesEnabled () {
    if(typeof window.matchMedia != "undefined" || typeof window.msMatchMedia != "undefined") {
        return true;
    } else {
        return false;
    }
}

Or more elegantly:

function mediaQueriesEnabled () {
    return (typeof window.matchMedia != "undefined" || typeof window.msMatchMedia != "undefined");
}

JSFiddle

I've tested in the following browsers that support media queries, all correctly returned true:

• Safari Mobile
• Chrome 26

I've tested in the following browsers that do not support media queries, all correctly returned false:

• IE 7

回答3:

Here's some working code that is based on @Kolink's answer. So far this code works great... I'll post back to this thread if I have any edits.

The Javascript:

var $globals = {
    mediaQuerySupport: false
}

function initMediaQueries () {
    // tests for media query support
    $globals.mediaQuerySupport = false;
    var d = document.createElement('div');
    d.className = "mediatest"; // found in core.css
    document.body.appendChild(d);
    if( window.getComputedStyle && window.getComputedStyle(d).position == "absolute") {
        $mlGlobals.mediaQuerySupport = true;
        mlDebug ('browser has media query support');
    }
    document.body.removeChild(d);
}

function mediaQueriesEnabled () {
   return ($globals.mediaQuerySupport);
}

$(document).ready(function() {
    initMediaQueries();
    if (mediaQueriesEnabled()) {
        ... do something
    }
});

The CSS (I added this to my main stylesheet file):

@media all and (min-width:1px) {
    .mediatest {position:absolute}
}