一键设置网页置灰 css写法，但是css在IE中兼容可能不太好

html{-webkit-filter: grayscale(100%);/* webkit */-moz-filter: grayscale(100%);/*firefox*/-ms-filter: grayscale(100%);/*ie9*/-o-filter: grayscale(100%);/*opera*/filter: grayscale(100%);filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);-webkit-filter: gray;filter: gray;
}
body{filter:gray; /*ie9- */background : none!important;
}

grayscale.js 通过js控制

调用

//1、整个页面变成灰色
grayscale(document.body);  //2、指定某个元素变灰色
grayscale(document.getElementById(元素ID));//3、指定某个元素不变成灰色
grayscale.reset(document.getElementById(元素ID));

以下是grayscale.js

/** -- grayscale.js --* Copyright (C) James Padolsey (http://james.padolsey.com)**/var grayscale = (function(){var config = {colorProps: ['color','backgroundColor','borderBottomColor','borderTopColor','borderLeftColor','borderRightColor','backgroundImage'],externalImageHandler : {/* Grayscaling externally hosted images does not work- Use these functions to handle those images as you so desire *//* Out of convenience these functions are also used for browserslike Chrome that do not support CanvasContext.getImageData */init : function(el, src) {if (el.nodeName.toLowerCase() === 'img') {// Is IMG element...} else {// Is background-image element:// Default - remove background imagesdata(el).backgroundImageSRC = src;el.style.backgroundImage = '';}},reset : function(el) {if (el.nodeName.toLowerCase() === 'img') {// Is IMG element...} else {// Is background-image element:el.style.backgroundImage = 'url(' + (data(el).backgroundImageSRC || '') + ')';}}}},log = function(){try { window.console.log.apply(console, arguments); }catch(e) {};},isExternal = function(url) {// Checks whether URL is external: 'CanvasContext.getImageData'// only works if the image is on the current domain.return (new RegExp('https?://(?!' + window.location.hostname + ')')).test(url);},data = (function(){var cache = [0],expando = 'data' + (+new Date());return function(elem) {var cacheIndex = elem[expando],nextCacheIndex = cache.length;if(!cacheIndex) {cacheIndex = elem[expando] = nextCacheIndex;cache[cacheIndex] = {};}return cache[cacheIndex];};})(),desatIMG = function(img, prepare, realEl) {// realEl is only set when img is temp (for BG images)var canvas = document.createElement('canvas'),context = canvas.getContext('2d'),height = img.naturalHeight || img.offsetHeight || img.height,width = img.naturalWidth || img.offsetWidth || img.width,imgData;canvas.height = height;canvas.width = width;context.drawImage(img, 0, 0);try {imgData = context.getImageData(0, 0, width, height);} catch(e) {}if (prepare) {desatIMG.preparing = true;// Slowly recurse through pixels for prep,// :: only occurs on grayscale.prepare()var y = 0;(function(){if (!desatIMG.preparing) { return; }if (y === height) {// Finished!context.putImageData(imgData, 0, 0, 0, 0, width, height);realEl ? (data(realEl).BGdataURL = canvas.toDataURL()): (data(img).dataURL = canvas.toDataURL())}for (var x = 0; x < width; x++) {var i = (y * width + x) * 4;// Apply Monoschrome level across all channels:imgData.data[i] = imgData.data[i+1] = imgData.data[i+2] =RGBtoGRAYSCALE(imgData.data[i], imgData.data[i+1], imgData.data[i+2]);}y++;setTimeout(arguments.callee, 0);})();return;} else {// If desatIMG was called without 'prepare' flag// then cancel recursion and proceed with force! (below)desatIMG.preparing = false;}for (var y = 0; y < height; y++) {for (var x = 0; x < width; x++) {var i = (y * width + x) * 4;// Apply Monoschrome level across all channels:imgData.data[i] = imgData.data[i+1] = imgData.data[i+2] =RGBtoGRAYSCALE(imgData.data[i], imgData.data[i+1], imgData.data[i+2]);}}context.putImageData(imgData, 0, 0, 0, 0, width, height);return canvas;},getStyle = function(el, prop) {var style = document.defaultView && document.defaultView.getComputedStyle ? document.defaultView.getComputedStyle(el, null)[prop]: el.currentStyle[prop];// If format is #FFFFFF: (convert to RGB)if (style && /^#[A-F0-9]/i.test(style)) {var hex = style.match(/[A-F0-9]{2}/ig);style = 'rgb(' + parseInt(hex[0], 16) + ','+ parseInt(hex[1], 16) + ','+ parseInt(hex[2], 16) + ')';}return style;},RGBtoGRAYSCALE = function(r,g,b) {// Returns single monochrome figure:return parseInt( (0.2125 * r) + (0.7154 * g) + (0.0721 * b), 10 );},getAllNodes = function(context) {var all = Array.prototype.slice.call(context.getElementsByTagName('*'));all.unshift(context);return all;};var init = function(context) {// Handle if a DOM collection is passed instead of a single el:if (context && context[0] && context.length && context[0].nodeName) {// Is a DOM collection:var allContexts = Array.prototype.slice.call(context),cIndex = -1, cLen = allContexts.length;while (++cIndex -1) {var urlPatt = /\(['"]?(.+?)['"]?\)/,url = style.match(urlPatt)[1];if (isExternal(url)) {config.externalImageHandler.init(cur, url);data(cur).externalBG = true;continue;}// data(cur).BGdataURL refers to caches URL (from preparation)try {var imgSRC = data(cur).BGdataURL || (function(){var temp = document.createElement('img');temp.src = url;return desatIMG(temp).toDataURL();})();cur.style[prop] = style.replace(urlPatt, function(_, url){return '(' + imgSRC + ')';});} catch(e) { config.externalImageHandler.init(cur, url); }}}}}};init.reset = function(context) {// Handle if a DOM collection is passed instead of a single el:if (context && context[0] && context.length && context[0].nodeName) {// Is a DOM collection:var allContexts = Array.prototype.slice.call(context),cIndex = -1, cLen = allContexts.length;while (++cIndex -1) {var urlPatt = /\(['"]?(.+?)['"]?\)/,url = style.match(urlPatt)[1];if (!isExternal(url)) {var temp = document.createElement('img');temp.src = url;desatIMG(temp, true, cur);}}}}};return init;})();