如何在javascript中检测浏览器渲染引擎？

时间：2011-05-31 14:35:25

标签： javascript rendering-engine

我读了一本名为“专业Javascript For Web Developers第2版”的书，并声明该代码可以检测浏览器渲染引擎：

    <script type="text/javascript">
  var client = function(){
     var engine = {
        ie: 0,
        gecko: 0,
        webkit: 0,
        khtml: 0,
        opera: 0,

        ver: null
     };

     return {
        engine : engine  
     };

  }();

  if(client.engine.ie){
      alert("This is internet explorer");
  }else if(client.engine.gecko > 1.5){
      if(client.engine.ver == "1.8.1"){
          alert("This is gecko rendering browser");
      }
  }else if(client.engine.webkit){
        alert("This is web kit");
  }else if(client.engine.khtml){
       alert("This is khtml");
  }else{
       alert("none of the above");
  }
</script>

但似乎不起作用，那么这段代码如何检测浏览器渲染引擎呢？谢谢

3 个答案:

答案 0 :(得分：10)

如果您阅读chapter和download the source

的其余部分

然后你可以看看client.js：

它仍可在win7上的IE10和Win10上的Chrome 67上运行

处理IE11（Trident /）和Edge（Edge /）需要稍加改动 - 稍后见

var client = function() {

  //rendering engines
  var engine = {
    ie: 0,
    gecko: 0,
    webkit: 0,
    khtml: 0,
    opera: 0,

    //complete version
    ver: null
  };

  //browsers
  var browser = {

    //browsers
    ie: 0,
    firefox: 0,
    safari: 0,
    konq: 0,
    opera: 0,
    chrome: 0,
    safari: 0,

    //specific version
    ver: null
  };


  //platform/device/OS
  var system = {
    win: false,
    mac: false,
    x11: false,

    //mobile devices
    iphone: false,
    ipod: false,
    nokiaN: false,
    winMobile: false,
    macMobile: false,

    //game systems
    wii: false,
    ps: false
  };

  //detect rendering engines/browsers
  var ua = navigator.userAgent;
  if (window.opera) {
    engine.ver = browser.ver = window.opera.version();
    engine.opera = browser.opera = parseFloat(engine.ver);
  } else if (/AppleWebKit\/(\S+)/.test(ua)) {
    engine.ver = RegExp["$1"];
    engine.webkit = parseFloat(engine.ver);

    //figure out if it's Chrome or Safari
    if (/Chrome\/(\S+)/.test(ua)) {
      browser.ver = RegExp["$1"];
      browser.chrome = parseFloat(browser.ver);
    } else if (/Version\/(\S+)/.test(ua)) {
      browser.ver = RegExp["$1"];
      browser.safari = parseFloat(browser.ver);
    } else {
      //approximate version
      var safariVersion = 1;
      if (engine.webkit < 100) {
        safariVersion = 1;
      } else if (engine.webkit < 312) {
        safariVersion = 1.2;
      } else if (engine.webkit < 412) {
        safariVersion = 1.3;
      } else {
        safariVersion = 2;
      }

      browser.safari = browser.ver = safariVersion;
    }
  } else if (/KHTML\/(\S+)/.test(ua) || /Konqueror\/([^;]+)/.test(ua)) {
    engine.ver = browser.ver = RegExp["$1"];
    engine.khtml = browser.konq = parseFloat(engine.ver);
  } else if (/rv:([^\)]+)\) Gecko\/\d{8}/.test(ua)) {
    engine.ver = RegExp["$1"];
    engine.gecko = parseFloat(engine.ver);

    //determine if it's Firefox
    if (/Firefox\/(\S+)/.test(ua)) {
      browser.ver = RegExp["$1"];
      browser.firefox = parseFloat(browser.ver);
    }
  } else if (/MSIE ([^;]+)/.test(ua)) { // add Trident/ to test IE11, Edge for Edge
    engine.ver = browser.ver = RegExp["$1"];
    engine.ie = browser.ie = parseFloat(engine.ver);
  }

  //detect browsers
  browser.ie = engine.ie;
  browser.opera = engine.opera;


  //detect platform
  var p = navigator.platform;
  system.win = p.indexOf("Win") == 0;
  system.mac = p.indexOf("Mac") == 0;
  system.x11 = (p == "X11") || (p.indexOf("Linux") == 0);

  //detect windows operating systems
  if (system.win) {
    if (/Win(?:dows )?([^do]{2})\s?(\d+\.\d+)?/.test(ua)) {
      if (RegExp["$1"] == "NT") {
        switch (RegExp["$2"]) {
          case "5.0":
            system.win = "2000";
            break;
          case "5.1":
            system.win = "XP";
            break;
          case "6.0":
            system.win = "Vista";
            break;
          default:
            system.win = "NT";
            break;
        }
      } else if (RegExp["$1"] == "9x") {
        system.win = "ME";
      } else {
        system.win = RegExp["$1"];
      }
    }
  }

  //mobile devices
  system.iphone = ua.indexOf("iPhone") > -1;
  system.ipod = ua.indexOf("iPod") > -1;
  system.nokiaN = ua.indexOf("NokiaN") > -1;
  system.winMobile = (system.win == "CE");
  system.macMobile = (system.iphone || system.ipod);

  //gaming systems
  system.wii = ua.indexOf("Wii") > -1;
  system.ps = /playstation/i.test(ua);

  //return it
  return {
    engine: engine,
    browser: browser,
    system: system
  };

}();

console.log(client.browser,client.engine,client.system)

处理IE11（Trident /）和Edge（Edge /）

需要稍加改动 

var client = function() {

  //rendering engines
  var engine = {
    ie: 0,
    edge: 0,
    gecko: 0,
    webkit: 0,
    khtml: 0,
    opera: 0,

    //complete version
    ver: null
  };

  //browsers
  var browser = {

    //browsers
    ie: 0,
    edge: 0,
    firefox: 0,
    safari: 0,
    konq: 0,
    opera: 0,
    chrome: 0,
    safari: 0,

    //specific version
    ver: null
  };


  //platform/device/OS
  var system = {
    win: false,
    mac: false,
    x11: false,

    //mobile devices
    iphone: false,
    ipod: false,
    nokiaN: false,
    winMobile: false,
    macMobile: false,

    //game systems
    wii: false,
    ps: false
  };

  //detect rendering engines/browsers
  var ua = navigator.userAgent;
  if (window.opera) {
    engine.ver = browser.ver = window.opera.version();
    engine.opera = browser.opera = parseFloat(engine.ver);
  }  
  else if (/Edge\/([^;]+)/.test(ua)) { // IE11
    engine.ver = browser.ver = RegExp["$1"];
    engine.edge = browser.edge = parseFloat(engine.ver);
  } else if (/AppleWebKit\/(\S+)/.test(ua)) {
    engine.ver = RegExp["$1"];
    engine.webkit = parseFloat(engine.ver);

    //figure out if it's Chrome or Safari
    if (/Chrome\/(\S+)/.test(ua)) {
      browser.ver = RegExp["$1"];
      browser.chrome = parseFloat(browser.ver);
    } else if (/Version\/(\S+)/.test(ua)) {
      browser.ver = RegExp["$1"];
      browser.safari = parseFloat(browser.ver);
    } else {
      //approximate version
      var safariVersion = 1;
      if (engine.webkit < 100) {
        safariVersion = 1;
      } else if (engine.webkit < 312) {
        safariVersion = 1.2;
      } else if (engine.webkit < 412) {
        safariVersion = 1.3;
      } else {
        safariVersion = 2;
      }

      browser.safari = browser.ver = safariVersion;
    }
  } else if (/KHTML\/(\S+)/.test(ua) || /Konqueror\/([^;]+)/.test(ua)) {
    engine.ver = browser.ver = RegExp["$1"];
    engine.khtml = browser.konq = parseFloat(engine.ver);
  } else if (/rv:([^\)]+)\) Gecko\/\d{8}/.test(ua)) {
    engine.ver = RegExp["$1"];
    engine.gecko = parseFloat(engine.ver);

    //determine if it's Firefox
    if (/Firefox\/(\S+)/.test(ua)) {
      browser.ver = RegExp["$1"];
      browser.firefox = parseFloat(browser.ver);
    }
  } else if (/MSIE ([^;]+)/.test(ua)) { // IE <= 10
    engine.ver = browser.ver = RegExp["$1"];
    engine.ie = browser.ie = parseFloat(engine.ver);
  } else if (/Trident\/([^;]+)/.test(ua)) { // IE11
    engine.ver = RegExp["$1"];
    browser.ver = parseFloat(ua.split("rv:")[1]);
    engine.ie = parseFloat(browser.ver);
  }

  //detect browsers
  browser.ie = engine.ie;
  browser.opera = engine.opera;


  //detect platform
  var p = navigator.platform;
  system.win = p.indexOf("Win") == 0;
  system.mac = p.indexOf("Mac") == 0;
  system.x11 = (p == "X11") || (p.indexOf("Linux") == 0);

  //detect windows operating systems
  if (system.win) {
    if (/Win(?:dows )?([^do]{2})\s?(\d+\.\d+)?/.test(ua)) {
      if (RegExp["$1"] == "NT") {
        switch (RegExp["$2"]) {
          case "5.0":
            system.win = "2000";
            break;
          case "5.1":
            system.win = "XP";
            break;
          case "6.0":
            system.win = "Vista";
            break;
          default:
            system.win = "NT";
            break;
        }
      } else if (RegExp["$1"] == "9x") {
        system.win = "ME";
      } else {
        system.win = RegExp["$1"];
      }
    }
  }

  //mobile devices
  system.iphone = ua.indexOf("iPhone") > -1;
  system.ipod = ua.indexOf("iPod") > -1;
  system.nokiaN = ua.indexOf("NokiaN") > -1;
  system.winMobile = (system.win == "CE");
  system.macMobile = (system.iphone || system.ipod);

  //gaming systems
  system.wii = ua.indexOf("Wii") > -1;
  system.ps = /playstation/i.test(ua);

  //return it
  return {
    engine: engine,
    browser: browser,
    system: system
  };

}();

console.log(JSON.stringify({ browser:client.browser,engine:client.engine,system:client.system},null, 2));

答案 1 :(得分：1)

脚本显然不起作用 - 它只是将一堆变量设置为零或null，然后检查它们是零还是空。我的猜测是，这不是整个剧本，并且缺少关键部分。

通常做的是读取UserAgent字符串（我懒得谷歌你究竟是怎么做的）并在其上抛出一些正则表达式来检测已知模式。这种用户代理嗅探有一些缺点：

  1. 它不向前兼容。您不知道未来的浏览器将使用哪种UA字符串，因此最有可能的是，较新的浏览器将无法通过您的测试并获得最简化的版本，即使它们可以轻松处理全眼睛的糖果 - 你的 - 一个。

  2. UA字符串不可靠。仅仅因为许多网站犯了嗅探错误，然后没有定期更新，用户设置了不同的UA字符串，故意报告“错误的”渲染引擎。然后他们忘记将其切换回来，造成各种奇怪的行为。

  3. 仅仅因为某人拥有某个渲染引擎并不意味着您可以依赖所有功能。浏览器具有高度可配置性，人们使用各种扩展，有选择地或完全阻止事物。

    4. 长话短说，而不是嗅探UA字符串并假设事物是您认为的，只是单独和直接测试功能。

答案 2 :(得分：0)

这只是一种选择。如果您真的担心渲染问题，就设计而言，您可以随时使用屏幕宽度的游乐场。

对于单页应用程序，您只需根据屏幕宽度和要求将屏幕筛选为正确的尺寸......：）

我们利用了：

if(screen.width > 360 && screen.width < 720){
    document.write ('<meta name="viewport" content="initial-scale=.25, maximum-scale=.25, user-scalable=no">');
 }

对于ios，iphone，ipad，它非常简单，因为你必须使用固定尺寸或标准尺寸。

对于Android，真的让你感到沮丧，我们发现好的是推进ldpi，mdpi，hdpi，xhdi和max xxhdpi（对于标签）像素范围。

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