转：
从html5打开本地的app–如果本地没有app就跳转到下载页面，大家都会认为这是一项很简单的操作。网上的教程也很多，但是可行性都不高。因为手机系统和浏览器型号各不相同，所以兼容性会是让各个前端工程师头疼的问题。我们不妨看一下京东是如何解决的。京东的原代码已经混淆过了，我只能一点点反混淆并注释。
网上的文章千篇一律 都是采用window.location.href的方式打开的，但是这种方法的兼容性非常的渣。在ios的safari浏览器中无法使用，会出现还未打开app就自动跳转到下载页面的情况，影响用户的使用。那么我们来看一下京东是如何解决兼容性的问题。
1 (function(){ 2 // 判断浏览器 3 var Navigator = navigator.userAgent; 4 var ifChrome = Navigator.match(/Chrome/i) != null && Navigator.match(/Version\/\d+\.\d+(\.\d+)?\sChrome\//i) == null ? true : false; 5 var ifAndroid = (Navigator.match(/(Android);?[\s\/]+([\d.]+)?/)) ? true : false; 6 var ifiPad = (Navigator.match(/(iPad).*OS\s([\d_]+)/)) ? true : false; 7 var ifiPhone = (!ifiPad && Navigator.match(/(iPhone\sOS)\s([\d_]+)/)) ? true : false; 8 var ifSafari = (ifiPhone || ifiPad) && Navigator.match(/Safari/); 9 var version = 0; 10 ifSafari && (version = Navigator.match(/Version\/([\d\.]+)/)); 11 12 version = parseFloat(version[1], 10); 13 // 是否从微信打开 14 var ifWeixin = navigator.userAgent.indexOf("MicroMessenger") >= 0; // weixin 15 var j = false; 16 var iframe = "plugIn_downloadAppPlugIn_loadIframe"; 17 var t = false; 18 var i = 0; 19 var B = {}; 20 var b = {}; 21 var selector = null; 22 var Hquery = {}; 23 // 判断当前使用的js框架是zepto还是jquery 24 var Query = window.Zepto || window.jQuery ? true : false; 25 var g = []; 26 // 是否存在html5的localStorage 存储 27 var v = window.localStorage ? true : false; 28 var o = "mdownloadAppPlugInskip"; 29 var p = null; 30 31 function m() { // 打印时间 例如:2016-5-18 32 var M = new Date(); 33 var N = M.getFullYear(); 34 var O = M.getMonth() + 1; 35 var L = M.getDate(); 36 strDate = N + "-" + O + "-" + L; 37 return strDate 38 } 39 // 微信相关操作 40 function r() { // weixin api 41 WeixinJSBridge.invoke("getInstallState", { 42 packageName: "com.jingdong.app.mall", 43 packageUrl: "openApp.jdMobile://" 44 }, function(M) { 45 var N = M.err_msg, 46 L = 0; 47 if (N.indexOf("get_install_state:yes") > -1) { 48 j = true 49 } 50 }) 51 } 52 // 根据是否存在js框架进行dom和时间的绑定 53 function bind(dom, event, fun) { // bind event 54 if (Query) { 55 selector("#" + dom).bind(event, fun) 56 } else { 57 selector("#" + dom).addEventListener(event, fun, !1) 58 } 59 } 60 61 function z(L) { 62 var M = (L || "mGen") + (++i); 63 return M 64 } 65 // 微信操作 66 if (ifWeixin) { // if navigitor is weixin 67 if (window.WeixinJSBridge && WeixinJSBridge.invoke) { 68 r() 69 } else { 70 document.addEventListener("WeixinJSBridgeReady", r, !1) 71 } 72 } 73 74 // 如果存在js框架 75 if (Query) { 76 selector = window.$; 77 Hquery = window.$ 78 } else { 79 selector = function(obj) { 80 if (typeof obj == "object") { 81 return obj 82 } 83 return document.querySelector(obj); 84 }; 85 if (!window.$) { 86 window.$ = Hquery = selector 87 } else { 88 Hquery = window.$ 89 } 90 } 91 window.onblur = function() { 92 for (var L = 0; L < g.length; L++) { 93 clearTimeout(g[L]) 94 } 95 }; 96 // 设置cookie。 97 function e(N) { 98 var M = document.cookie.indexOf(N + "="); 99 if (M == -1) {100 return ""101 }102 M = M + N.length + 1;103 var L = document.cookie.indexOf(";", M);104 if (L == -1) {105 L = document.cookie.length106 }107 return document.cookie.substring(M, L)108 }109 // 设置cookie110 function l(N, P, L, Q, O) { 111 var R = N + "=" + escape(P);112 if (L != "") {113 var M = new Date();114 M.setTime(M.getTime() + L * 24 * 3600 * 1000);115 R += ";expires=" + M.toGMTString()116 }117 if (Q != "") {118 R += ";path=" + Q119 }120 if (O != "") {121 R += ";domain=" + O122 }123 document.cookie = R124 }125 126 // 打开的链接集合127 function F(L) {128 var url = {129 downAppURl: "http://h5.m.jd.com/active/download/download.html?channel=jd-m",130 downAppIos: "http://union.m.jd.com/download/go.action?to=http%3A%2F%2Fitunes.apple.com%2Fcn%2Fapp%2Fid414245413&client=apple&unionId=12532&subunionId=m-top&key=e4dd45c0f480d8a08c4621b4fff5de74",131 downWeixin: "http://a.app.qq.com/o/simple.jsp?pkgname=com.jingdong.app.mall&g_f=991850",132 downIpad: "https://itunes.apple.com/cn/app/jing-dong-hd/id434374726?mt=8",133 inteneUrl: "openApp.jdMobile://360buy?type=1",134 inteneUrlParams: null,135 openAppBtnId: "",136 closePanelBtnId: "",137 closePanelId: "",138 closeCallblack: null,139 closeCallblackSource: null,140 cookieFlag: null,141 noRecord: false,142 sourceType: "JSHOP_SOURCE_TYPE",143 sourceValue: "JSHOP_SOURCE_VALUE",144 openAppEventId: "MDownLoadFloat_OpenNow",145 closePanelEventId: "MDownLoadFloat_Close"146 };147 if (L) {148 for (var M in L) {149 if (M && L[M]) {150 url[M] = L[M]151 }152 }153 }154 return url155 }156 // 敲黑板 重点内容。看京东是怎么解决兼容问题的。157 function openApp(N, L) { // openApp158 var R = h(N); //获取相对应的url159 var O = null;160 if (ifWeixin) { // 如果是微信端161 var M = null;162 if (j) {163 M = R164 } else {165 M = N.downWeixin166 }167 location.href = M; // 直接使用location.href打开168 return169 }170 if (ifiPad) { // 如果是ipad171 O = N.downIpad172 } else { 173 if (ifiPhone) { // 如果是iphone174 O = N.downAppIos175 } else {176 O = N.downAppURl177 }178 }179 180 if (ifChrome) { // 如果是chrome181 if (ifAndroid) { //安卓浏览器182 var Q = R;183 R = y(Q);184 // 延后50毫秒185 setTimeout(function() {186 window.location.href = R 187 }, 50)188 }189 }190 if (ifSafari && version >= 9) { // 判断safari版本 如果大于9191 setTimeout(function() { // 必须要使用settimeout192 var S = document.createElement("a"); //创建a元素193 S.setAttribute("href", R), S.style.display = "none", document.body.appendChild(S);194 var T = document.createEvent("HTMLEvents"); // 返回新创建的 Event 对象，具有指定的类型。195 T.initEvent("click", !1, !1)// 初始化新事件对象的属性, S.dispatchEvent(T) // 绑定事件196 }, 0)197 } else {198 document.querySelector("#" + iframe).src = R // 将iframe增加src199 }200 var P = Date.now();201 setTimeout(function() {202 if (L) {203 var S = setTimeout(function() {204 x(P, O)205 }, 1500);206 g.push(S)207 }208 }, 100)209 }210 // x方法211 function x(N, downUrl) {212 var L = Date.now();213 if (N && (L - N) < (1500 + 200)) {214 window.location.href = downUrl215 }216 }217 218 function h(N) {219 var V = [];220 var P = N.inteneUrlParams;221 var T = {222 category: "jump",223 des: "productDetail"224 };225 if (N.sourceType && N.sourceValue) {226 T.sourceType = N.sourceType;227 T.sourceValue = N.sourceValue;228 if (P && !P.sourceType && !P.sourceValue) {229 P.sourceType = N.sourceType;230 P.sourceValue = N.sourceValue231 }232 }233 if (P) {234 for (var U in P) {235 if (U && P[U]) {236 V.push('"' + U + '":"' + P[U] + '"')237 }238 }239 } else {240 for (var U in T) {241 if (U && T[U]) {242 V.push('"' + U + '":"' + T[U] + '"')243 }244 }245 }246 try {247 var Q = MPing.EventSeries.getSeries();248 if (Q) {249 var W = JSON.parse(Q);250 W.jdv = encodeURIComponent(e("__jdv"));251 W.unpl = encodeURIComponent(e("unpl"));252 W.mt_xid = encodeURIComponent(e("mt_xid"));253 W.mt_subsite = encodeURIComponent(e("mt_subsite"))254 }255 var S = {256 mt_subsite: encodeURIComponent(e("mt_subsite")),257 __jdv: encodeURIComponent(e("__jdv")),258 unpl: encodeURIComponent(e("unpl")),259 __jda: encodeURIComponent(e("__jda"))260 };261 Q = JSON.stringify(W);262 V.push('"m_param":' + Q);263 V.push('"SE":' + JSON.stringify(S))264 } catch (R) {265 V.push('"m_param":null')266 }267 var M = "{ " + V.join(",") + "}";268 var O = N.inteneUrl.split("?");269 var L = null;270 if (O.length == 2) {271 L = O[0] + "?" + O[1] + "¶ms=" + M272 } else {273 L = O[0] + "?params=" + M274 }275 return L276 }277 278 function y(L) {279 return "intent://m.jd.com/#Intent;scheme=" + L + ";package=com.jingdong.app.mall;end"280 }281 282 function n(L) {283 if (L.openAppBtnId) {284 B[L.openAppBtnId] = L;285 G(L.openAppBtnId, L.openAppEventId);286 bind(L.openAppBtnId, "click", function() {287 var P = this.getAttribute("id");288 var M = B[P];289 if (!t) {290 var N = document.createElement("iframe");291 N.id = iframe;292 document.body.appendChild(N);293 document.getElementById(iframe).style.display = "none";294 document.getElementById(iframe).style.width = "0px";295 document.getElementById(iframe).style.height = "0px";296 t = true297 }298 var O = M.cookieFlag ? "downloadAppPlugIn_downCloseDate_" + M.cookieFlag : "downloadAppPlugIn_downCloseDate";299 l(O, Date.now() + "_2592000000", 60, "/", "m.jd.com");300 l(O, Date.now() + "_2592000000", 60, "/", "m.jd.hk");301 openApp(M, true)302 })303 }304 }305 306 function D(M) {307 if (M.closePanelBtnId && M.closePanelId) {308 B[M.closePanelBtnId] = M;309 G(M.closePanelBtnId, M.closePanelEventId);310 var Q = M.cookieFlag ? "downloadAppPlugIn_downCloseDate_" + M.cookieFlag : "downloadAppPlugIn_downCloseDate";311 var O = e(Q);312 var P = null;313 if (O) {314 P = O.split("_");315 if (P.length == 2) {316 P[0] = parseInt(P[0], 10);317 P[1] = parseInt(P[1], 10)318 } else {319 P = null320 }321 }322 var L = Date.now();323 if (Html5Plus() || (!M.noRecord && P && P.length == 2 && (L - P[0]) < P[1])) {324 document.querySelector("#" + M.closePanelId).style.display = "none";325 if (M.closeCallblack) {326 var N = M.closeCallblackSource ? M.closeCallblackSource : null;327 M.closeCallblack.call(N)328 }329 return330 } else {331 document.querySelector("#" + M.closePanelId).style.display = "block"332 }333 bind(M.closePanelBtnId, "click", function() {334 var U = this.getAttribute("id");335 var R = B[U];336 var T = R.cookieFlag ? "downloadAppPlugIn_downCloseDate_" + R.cookieFlag : "downloadAppPlugIn_downCloseDate";337 if (!R.noRecord) {338 l(T, Date.now() + "_259200000", 60, "/", "m.jd.com");339 l(T, Date.now() + "_259200000", 60, "/", "m.jd.hk")340 }341 document.querySelector("#" + R.closePanelId).style.display = "none";342 if (R.closeCallblack) {343 var S = R.closeCallblackSource ? R.closeCallblackSource : null;344 R.closeCallblack.call(S)345 }346 })347 }348 }349 350 function Html5Plus() { // htmlplus351 if (Navigator.indexOf("Html5Plus") >= 0) {352 return true353 } else {354 return false355 }356 }357 358 function G(P, M) {359 try {360 var O = document.getElementById(P);361 var L = O.className;362 if (L) {363 L = L + " J_ping"364 } else {365 L = "J_ping"366 }367 O.className = L;368 O.setAttribute("report-eventid", M)369 } catch (N) {}370 }371 372 function C(L) {373 var M = F(L);374 n(M);375 D(M)376 }377 Hquery.downloadAppPlugIn = C;378 Hquery.downloadAppPlugInOpenApp = function(L) {379 var M = F(L);380 openApp(M);381 }382 });