[removed] Removing media query from external css f

问题:

How could I remove media query loaded from external css file (<link rel="stylesheet" type="text/css" href="XXXX.css" media="screen">)? Note that I cant disable the entire link tag because other important styles are included out of that media query:

body{...}
.container{...}
...
@media(min-width:XXXpx) {
....
}
...

Thank you!

回答1:

I strongly recommend pure CSS solution for this problem, such as defining a new stylesheet overwritting rules you don't want.

#selector {
    color: #000;
}

.some-classs-you-want-to-reserve {/*..*/}

@media only screen and (min-width: 600px) {
    /* unwanted */
    #selector {
        display: none;
    }
}

For example, if you want to mute rules inside @media only screen and (min-width: 600px), simply add a new stylesheet overwritting them to default values:

@media only screen and (min-width: 600px) {
    /* unwanted */
    #selector {
        display: block;
    }
}

If you insist on using Javascript, you can access and modify css rules by iterating document.styleSheets.

• https://developer.mozilla.org/en-US/docs/Web/API/StyleSheetList
• https://developer.mozilla.org/en-US/docs/Web/API/document.styleSheets

This is an instance of StyleSheetList, an array-like object. Each item of it represents an external or inline css stylesheet. All rules including media queries can be found inside it.

A brief tree structure:

- document.styleSheets
   |- CSSStyleSheet
       |- cssRules
       |- media

So here's an example showing how to remove all rules defined inside @media only screen and (min-width: 600px) block:

function removeRule() {
    if(typeof window.CSSMediaRule !== "function") 
        return false; //Your browser doesn't support media query feature

    var s = document.styleSheets, r,
        i, j, k;

    if(!s) return false; //no style sheets found

    // walk throuth css sheets
    for(i=0; i<s.length; i++) {
        // get all rules
        r = s[i].cssRules; 
        if(!r) continue;

        for(j=0; j<r.length; j++) {
            //If there's a rule for media query
            if(r[j] instanceof CSSMediaRule &&
                    r[j].media.mediaText == "only screen and (min-width: 600px)") {
                for(k=0; k<r[j].cssRules.length; k++) {
                    // remove all rules of it
                    r[j].deleteRule(r[j].cssRules[k]);
                }
                return true;
            }
        }
    }
}
removeRule();

Or live fiddle: http://jsfiddle.net/e4h41qm2/

回答2:

The fact is, if you delete one media query, another one get's activated. So you have to do a loop till no media query is found:

function removeRule() {
    if (typeof window.CSSMediaRule !== 'function') {
        return false;
    }
    var styleSheets = document.styleSheets;
    var number = 0;

    if (!styleSheets) {
        return false;
    }

    for (i = 0; i < styleSheets.length; i++) {
        var styleSheet = styleSheets[i];
        var rules = styleSheet.cssRules;
        if (!rules) {
            continue;
        }
        for (var j = 0; j < rules.length; j++) {
            var cssText = rules[j].cssText;
            if (cssText.indexOf('@media') === 0) {
                number++;
                styleSheet.deleteRule(j);
            }
        }
    }
    if (number) {
        return number;
    }
    return 0;
}

function removeMediaQueries() {
    var num = removeRule();
    var total = num;
    while (num) {
        num = removeRule();
        total += num;
    }
    if (total) {
        console.info(total + ' media quer' + (total == 1 ? 'y' : 'ies' + ' removed'));
    } else {
        console.info('No media queries removed');
    }
}
removeMediaQueries();

If you put all this in one line you can generate a bookmark in your browser and have a fast way to test the design without media queries. Very useful for newsletter.

javascript:!function(){function e(){if("function"!=typeof window.CSSMediaRule)return!1;var e=document.styleSheets,n=0;if(!e)return!1;for(i=0;i<e.length;i++){var o=e[i],r=o.cssRules;if(r)for(var t=0;t<r.length;t++){var f=r[t].cssText;0===f.indexOf("@media")&&(n++,o.deleteRule(t))}}return n?n:0}function n(){for(var i=e(),n=i;i;)i=e(),n+=i;n?console.info(n+" media quer"+(1==n?"y":"ies removed")):console.info("No media queries removed")}n()}();

回答3:

You're probably better off overriding it instead of trying to delete it, but if you must:

style = document.styleSheets[0]; // or whatever stylesheet you want

[].forEach.call(style.cssRules || [], function(rule, i) {
    if (!rule.cssText.indexOf('@media(min-width:XXXpx') {
        style.deleteRule(i);
    }
});

Untested.