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media.match.js
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media.match.js
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/*! MediaMatch v.2.0.3 - Testing css media queries in Javascript. Authors & copyright (c) 2013: WebLinc, David Knight. */
window.matchMedia || (window.matchMedia = function (win) {
'use strict';
// Internal globals
var _doc = win.document,
_viewport = _doc.documentElement,
_queries = [],
_queryID = 0,
_type = '',
_features = {},
// only screen
// only screen and
// not screen
// not screen and
// screen
// screen and
_typeExpr = /\s*(only|not)?\s*(screen|print|[a-z\-]+)\s*(and)?\s*/i,
// (-vendor-min-width: 300px)
// (min-width: 300px)
// (width: 300px)
// (width)
// (orientation: portrait|landscape)
_mediaExpr = /^\s*\(\s*(-[a-z]+-)?(min-|max-)?([a-z\-]+)\s*(:?\s*([0-9]+(\.[0-9]+)?|portrait|landscape)(px|em|dppx|dpcm|rem|%|in|cm|mm|ex|pt|pc|\/([0-9]+(\.[0-9]+)?))?)?\s*\)\s*$/,
_timer = 0,
// Helper methods
/*
_matches
*/
_matches = function (media) {
// screen and (min-width: 400px), screen and (max-width: 500px)
var mql = (media.indexOf(',') !== -1 && media.split(',')) || [media],
mqIndex = mql.length - 1,
mqLength = mqIndex,
mq = null,
// not screen, screen
negateType = null,
negateTypeFound = '',
negateTypeIndex = 0,
negate = false,
type = '',
// (min-width: 400px), (min-width)
exprListStr = '',
exprList = null,
exprIndex = 0,
exprLength = 0,
expr = null,
prefix = '',
length = '',
unit = '',
value = '',
feature = '',
match = false;
if (media === '') {
return true;
}
do {
mq = mql[mqLength - mqIndex];
negate = false;
negateType = mq.match(_typeExpr);
if (negateType) {
negateTypeFound = negateType[0];
negateTypeIndex = negateType.index;
}
if (!negateType || ((mq.substring(0, negateTypeIndex).indexOf('(') === -1) && (negateTypeIndex || (!negateType[3] && negateTypeFound !== negateType.input)))) {
match = false;
continue;
}
exprListStr = mq;
negate = negateType[1] === 'not';
if (!negateTypeIndex) {
type = negateType[2];
exprListStr = mq.substring(negateTypeFound.length);
}
// Test media type
// Test type against this device or if 'all' or empty ''
match = type === _type || type === 'all' || type === '';
exprList = (exprListStr.indexOf(' and ') !== -1 && exprListStr.split(' and ')) || [exprListStr];
exprIndex = exprList.length - 1;
exprLength = exprIndex;
if (match && exprIndex >= 0 && exprListStr !== '') {
do {
expr = exprList[exprIndex].match(_mediaExpr);
if (!expr || !_features[expr[3]]) {
match = false;
break;
}
prefix = expr[2];
length = expr[5];
value = length;
unit = expr[7];
feature = _features[expr[3]];
// Convert unit types
if (unit) {
if (unit === 'px') {
// If unit is px
value = Number(length);
} else if (unit === 'em' || unit === 'rem') {
// Convert relative length unit to pixels
// Assumed base font size is 16px
value = 16 * length;
} else if (expr[8]) {
// Convert aspect ratio to decimal
value = (length / expr[8]).toFixed(2);
} else if (unit === 'dppx') {
// Convert resolution dppx unit to pixels
value = length * 96;
} else if (unit === 'dpcm') {
// Convert resolution dpcm unit to pixels
value = length * 0.3937;
} else {
// default
value = Number(length);
}
}
// Test for prefix min or max
// Test value against feature
if (prefix === 'min-' && value) {
match = feature >= value;
} else if (prefix === 'max-' && value) {
match = feature <= value;
} else if (value) {
match = feature === value;
} else {
match = !!feature;
}
// If 'match' is false, break loop
// Continue main loop through query list
if (!match) {
break;
}
} while (exprIndex--);
}
// If match is true, break loop
// Once matched, no need to check other queries
if (match) {
break;
}
} while (mqIndex--);
return negate ? !match : match;
},
/*
_setFeature
*/
_setFeature = function () {
// Sets properties of '_features' that change on resize and/or orientation.
var w = win.innerWidth || _viewport.clientWidth,
h = win.innerHeight || _viewport.clientHeight,
dw = win.screen.width,
dh = win.screen.height,
c = win.screen.colorDepth,
x = win.devicePixelRatio;
_features.width = w;
_features.height = h;
_features['aspect-ratio'] = (w / h).toFixed(2);
_features['device-width'] = dw;
_features['device-height'] = dh;
_features['device-aspect-ratio'] = (dw / dh).toFixed(2);
_features.color = c;
_features['color-index'] = Math.pow(2, c);
_features.orientation = (h >= w ? 'portrait' : 'landscape');
_features.resolution = (x && x * 96) || win.screen.deviceXDPI || 96;
_features['device-pixel-ratio'] = x || 1;
},
/*
_watch
*/
_watch = function () {
clearTimeout(_timer);
_timer = setTimeout(function () {
var query = null,
qIndex = _queryID - 1,
qLength = qIndex,
match = false;
if (qIndex >= 0) {
_setFeature();
do {
query = _queries[qLength - qIndex];
if (query) {
match = _matches(query.mql.media);
if ((match && !query.mql.matches) || (!match && query.mql.matches)) {
query.mql.matches = match;
if (query.listeners) {
for (var i = 0, il = query.listeners.length; i < il; i++) {
if (query.listeners[i]) {
query.listeners[i].call(win, query.mql);
}
}
}
}
}
} while(qIndex--);
}
}, 10);
},
/*
_init
*/
_init = function () {
var head = _doc.getElementsByTagName('head')[0],
style = _doc.createElement('style'),
info = null,
typeList = ['screen', 'print', 'speech', 'projection', 'handheld', 'tv', 'braille', 'embossed', 'tty'],
typeIndex = 0,
typeLength = typeList.length,
cssText = '#mediamatchjs { position: relative; z-index: 0; }',
eventPrefix = '',
addEvent = win.addEventListener || (eventPrefix = 'on') && win.attachEvent;
style.type = 'text/css';
style.id = 'mediamatchjs';
head.appendChild(style);
// Must be placed after style is inserted into the DOM for IE
info = (win.getComputedStyle && win.getComputedStyle(style)) || style.currentStyle;
// Create media blocks to test for media type
for ( ; typeIndex < typeLength; typeIndex++) {
cssText += '@media ' + typeList[typeIndex] + ' { #mediamatchjs { position: relative; z-index: ' + typeIndex + ' } }';
}
// Add rules to style element
if (style.styleSheet) {
style.styleSheet.cssText = cssText;
} else {
style.textContent = cssText;
}
// Get media type
_type = typeList[(info.zIndex * 1) || 0];
head.removeChild(style);
_setFeature();
// Set up listeners
addEvent(eventPrefix + 'resize', _watch, false);
addEvent(eventPrefix + 'orientationchange', _watch, false);
};
_init();
/*
A list of parsed media queries, ex. screen and (max-width: 400px), screen and (max-width: 800px)
*/
return function (media) {
var id = _queryID,
mql = {
matches : false,
media : media,
addListener : function addListener(listener) {
_queries[id].listeners || (_queries[id].listeners = []);
listener && _queries[id].listeners.push(listener);
},
removeListener : function removeListener(listener) {
var query = _queries[id],
i = 0,
il = 0;
if (!query) {
return;
}
il = query.listeners.length;
for ( ; i < il; i++) {
if (query.listeners[i] === listener) {
query.listeners.splice(i, 1);
}
}
}
};
if (media === '') {
mql.matches = true;
return mql;
}
mql.matches = _matches(media);
_queryID = _queries.push({
mql : mql,
listeners : null
});
return mql;
};
}(window));