javascript事件处理模型实例说明

var EventUtil = new Object;/**//*  此方法用来给特定对象添加事件，oTarget是指定对象,sEventType是事件类型，如click、keydown等，   fnHandler是事件回调函数*/EventUtil.addEventHandler = function (oTarget, sEventType, fnHandler) {   //firefox情况下   if (oTarget.addEventListener) {     oTarget.addEventListener(sEventType, fnHandler, false);   }   //IE下   else if (oTarget.attachEvent) {     oTarget.attachEvent("on" + sEventType, fnHandler);   }   else {     oTarget["on" + sEventType] = fnHandler;   }};/*  此方法用来移除特定对象的特定事件，oTarget是指定对象,sEventType是事件类型，如click、keydown等，fnHandler是事件回调函数*/   EventUtil.removeEventHandler = function (oTarget, sEventType, fnHandler) {   if (oTarget.removeEventListener) {     oTarget.removeEventListener(sEventType, fnHandler, false);   } else if (oTarget.detachEvent) {     oTarget.detachEvent("on" + sEventType, fnHandler);   } else {     oTarget["on" + sEventType] = null;   }};/*格式化事件，因为IE和其他浏览器下获取事件的方式不同并且事件的属性也不尽相同，通过此方法提供一个一致的事件*/EventUtil.formatEvent = function (oEvent) {   //isIE和isWin引用到一个js文件，判断浏览器和操作系统类型   if (isIE && isWin) {     oEvent.charCode = (oEvent.type == "keypress") ? oEvent.keyCode : 0;     //IE只支持冒泡，不支持捕获     oEvent.eventPhase = 2;     oEvent.isChar = (oEvent.charCode > 0);     oEvent.pageX = oEvent.clientX + document.body.scrollLeft;     oEvent.pageY = oEvent.clientY + document.body.scrollTop;     //阻止事件的默认行为     oEvent.preventDefault = function () {       this.returnValue = false;     };      //将toElement,fromElement转化为标准的relatedTarget     if (oEvent.type == "mouseout") {       oEvent.relatedTarget = oEvent.toElement;     } else if (oEvent.type == "mouseover") {       oEvent.relatedTarget = oEvent.fromElement;     }     //取消冒泡        oEvent.stopPropagation = function () {       this.cancelBubble = true;     };     oEvent.target = oEvent.srcElement;     //添加事件发生时间属性，IE没有     oEvent.time = (new Date).getTime();   }   return oEvent;};EventUtil.getEvent = function() {   if (window.event) {     //格式化IE的事件     return this.formatEvent(window.event);   } else {     return EventUtil.getEvent.caller.arguments[0];   }};

/**附带上一个判断浏览器和系统类型的js文件，通过引入一些名字显而易见的全局变量作为判断的结果，使用时需要小心变量名称冲突：*/var sUserAgent = navigator.userAgent;var fAppVersion = parseFloat(navigator.appVersion);function compareVersions(sVersion1, sVersion2) {  var aVersion1 = sVersion1.split(".");  var aVersion2 = sVersion2.split(".");    if (aVersion1.length > aVersion2.length) {    for (var i=0; i < aVersion1.length - aVersion2.length; i++) {      aVersion2.push("0");    }  } else if (aVersion1.length < aVersion2.length) {    for (var i=0; i < aVersion2.length - aVersion1.length; i++) {      aVersion1.push("0");    }    }    for (var i=0; i < aVersion1.length; i++) {     if (aVersion1[i] < aVersion2[i]) {      return -1;    } else if (aVersion1[i] > aVersion2[i]) {      return 1;    }    }    return 0;}var isOpera = sUserAgent.indexOf("Opera") > -1;var isMinOpera4 = isMinOpera5 = isMinOpera6 = isMinOpera7 = isMinOpera7_5 = false;if (isOpera) {  var fOperaVersion;  if(navigator.appName == "Opera") {    fOperaVersion = fAppVersion;  } else {    var reOperaVersion = new RegExp("Opera (//d+//.//d+)");    reOperaVersion.test(sUserAgent);    fOperaVersion = parseFloat(RegExp["$1"]);  }  isMinOpera4 = fOperaVersion >= 4;  isMinOpera5 = fOperaVersion >= 5;  isMinOpera6 = fOperaVersion >= 6;  isMinOpera7 = fOperaVersion >= 7;  isMinOpera7_5 = fOperaVersion >= 7.5;}var isKHTML = sUserAgent.indexOf("KHTML") > -1        || sUserAgent.indexOf("Konqueror") > -1        || sUserAgent.indexOf("AppleWebKit") > -1;        var isMinSafari1 = isMinSafari1_2 = false;var isMinKonq2_2 = isMinKonq3 = isMinKonq3_1 = isMinKonq3_2 = false;if (isKHTML) {  isSafari = sUserAgent.indexOf("AppleWebKit") > -1;  isKonq = sUserAgent.indexOf("Konqueror") > -1;  if (isSafari) {    var reAppleWebKit = new RegExp("AppleWebKit///(//d+(?://.//d*)?)");    reAppleWebKit.test(sUserAgent);    var fAppleWebKitVersion = parseFloat(RegExp["$1"]);    isMinSafari1 = fAppleWebKitVersion >= 85;    isMinSafari1_2 = fAppleWebKitVersion >= 124;  } else if (isKonq) {    var reKonq = new RegExp("Konqueror///(//d+(?://.//d+(?://.//d)?)?)");    reKonq.test(sUserAgent);    isMinKonq2_2 = compareVersions(RegExp["$1"], "2.2") >= 0;    isMinKonq3 = compareVersions(RegExp["$1"], "3.0") >= 0;    isMinKonq3_1 = compareVersions(RegExp["$1"], "3.1") >= 0;    isMinKonq3_2 = compareVersions(RegExp["$1"], "3.2") >= 0;  }   }var isIE = sUserAgent.indexOf("compatible") > -1       && sUserAgent.indexOf("MSIE") > -1      && !isOpera;      var isMinIE4 = isMinIE5 = isMinIE5_5 = isMinIE6 = false;if (isIE) {  var reIE = new RegExp("MSIE (//d+//.//d+);");  reIE.test(sUserAgent);  var fIEVersion = parseFloat(RegExp["$1"]);  isMinIE4 = fIEVersion >= 4;  isMinIE5 = fIEVersion >= 5;  isMinIE5_5 = fIEVersion >= 5.5;  isMinIE6 = fIEVersion >= 6.0;}var isMoz = sUserAgent.indexOf("Gecko") > -1      && !isKHTML;var isMinMoz1 = sMinMoz1_4 = isMinMoz1_5 = false;if (isMoz) {  var reMoz = new RegExp("rv:(//d+//.//d+(?://.//d+)?)");  reMoz.test(sUserAgent);  isMinMoz1 = compareVersions(RegExp["$1"], "1.0") >= 0;  isMinMoz1_4 = compareVersions(RegExp["$1"], "1.4") >= 0;  isMinMoz1_5 = compareVersions(RegExp["$1"], "1.5") >= 0;}var isNS4 = !isIE && !isOpera && !isMoz && !isKHTML       && (sUserAgent.indexOf("Mozilla") == 0)       && (navigator.appName == "Netscape")       && (fAppVersion >= 4.0 && fAppVersion < 5.0);var isMinNS4 = isMinNS4_5 = isMinNS4_7 = isMinNS4_8 = false;if (isNS4) {  isMinNS4 = true;  isMinNS4_5 = fAppVersion >= 4.5;  isMinNS4_7 = fAppVersion >= 4.7;  isMinNS4_8 = fAppVersion >= 4.8;}var isWin = (navigator.platform == "Win32") || (navigator.platform == "Windows");var isMac = (navigator.platform == "Mac68K") || (navigator.platform == "MacPPC")       || (navigator.platform == "Macintosh");var isUnix = (navigator.platform == "X11") && !isWin && !isMac;var isWin95 = isWin98 = isWinNT4 = isWin2K = isWinME = isWinXP = false;var isMac68K = isMacPPC = false;var isSunOS = isMinSunOS4 = isMinSunOS5 = isMinSunOS5_5 = false;if (isWin) {  isWin95 = sUserAgent.indexOf("Win95") > -1        || sUserAgent.indexOf("Windows 95") > -1;  isWin98 = sUserAgent.indexOf("Win98") > -1        || sUserAgent.indexOf("Windows 98") > -1;  isWinME = sUserAgent.indexOf("Win 9x 4.90") > -1        || sUserAgent.indexOf("Windows ME") > -1;  isWin2K = sUserAgent.indexOf("Windows NT 5.0") > -1        || sUserAgent.indexOf("Windows 2000") > -1;  isWinXP = sUserAgent.indexOf("Windows NT 5.1") > -1        || sUserAgent.indexOf("Windows XP") > -1;  isWinNT4 = sUserAgent.indexOf("WinNT") > -1        || sUserAgent.indexOf("Windows NT") > -1        || sUserAgent.indexOf("WinNT4.0") > -1        || sUserAgent.indexOf("Windows NT 4.0") > -1        && (!isWinME && !isWin2K && !isWinXP);} if (isMac) {  isMac68K = sUserAgent.indexOf("Mac_68000") > -1         || sUserAgent.indexOf("68K") > -1;  isMacPPC = sUserAgent.indexOf("Mac_PowerPC") > -1         || sUserAgent.indexOf("PPC") > -1; }if (isUnix) {  isSunOS = sUserAgent.indexOf("SunOS") > -1;  if (isSunOS) {    var reSunOS = new RegExp("SunOS (//d+//.//d+(?://.//d+)?)");    reSunOS.test(sUserAgent);    isMinSunOS4 = compareVersions(RegExp["$1"], "4.0") >= 0;    isMinSunOS5 = compareVersions(RegExp["$1"], "5.0") >= 0;    isMinSunOS5_5 = compareVersions(RegExp["$1"], "5.5") >= 0;  }}