javascript設計模式學習筆記

一、有一些比較經常使用的代碼能夠做爲積累，這樣在實現某個功能的時候能更快的達到目的，學習基礎是爲了看懂，可是要能應用除了本身寫，也應該積累比較好的代碼：

逐步嘗試每一種XHR對象，直到遇到當前的javascript環境支持的對象爲止。

/* SimpleXhrFactory singleton, step 1. */

var SimpleXhrFactory = (function() {

// The three branches. var standard = { createXhrObject: function() { return new XMLHttpRequest(); } }; var activeXNew = { createXhrObject: function() { return new ActiveXObject('Msxml2.XMLHTTP'); } }; var activeXOld = { createXhrObject: function() { return new ActiveXObject('Microsoft.XMLHTTP'); } };

})();

/* SimpleXhrFactory singleton, step 2. */

var SimpleXhrFactory = (function() {

// The three branches. var standard = { createXhrObject: function() { return new XMLHttpRequest(); } }; var activeXNew = { createXhrObject: function() { return new ActiveXObject('Msxml2.XMLHTTP'); } }; var activeXOld = { createXhrObject: function() { return new ActiveXObject('Microsoft.XMLHTTP'); } };

// To assign the branch, try each method; return whatever doesn't fail. var testObject; try { testObject = standard.createXhrObject(); return standard; // Return this if no error was thrown. } catch(e) { try { testObject = activeXNew.createXhrObject(); return activeXNew; // Return this if no error was thrown. } catch(e) { try { testObject = activeXOld.createXhrObject(); return activeXOld; // Return this if no error was thrown. } catch(e) { throw new Error('No XHR object found in this environment.'); } } }

})();

二、關於獲取當前瀏覽器信息的經常使用方法： //========= var browser=navigator.appName var b_version=navigator.appVersion var version=parseFloat(b_version) document.write("瀏覽器名稱："+ browser) document.write("<br />") document.write("瀏覽器版本："+ version) //============ document.write("<p>代碼：") document.write(navigator.appCodeName + "</p>")

document.write("<p>平臺：") document.write(navigator.platform + "</p>")

document.write("<p>Cookies 啓用：") document.write(navigator.cookieEnabled + "</p>")

document.write("<p>瀏覽器的用戶代理報頭：") document.write(navigator.userAgent + "</p>")

//========= var x = navigator; document.write("CodeName=" + x.appCodeName); document.write("<br />"); document.write("MinorVersion=" + x.appMinorVersion); document.write("<br />"); document.write("Name=" + x.appName); document.write("<br />"); document.write("Version=" + x.appVersion); document.write("<br />"); document.write("CookieEnabled=" + x.cookieEnabled); document.write("<br />"); document.write("CPUClass=" + x.cpuClass); document.write("<br />"); document.write("OnLine=" + x.onLine); document.write("<br />"); document.write("Platform=" + x.platform); document.write("<br />"); document.write("UA=" + x.userAgent); document.write("<br />"); document.write("BrowserLanguage=" + x.browserLanguage); document.write("<br />"); document.write("SystemLanguage=" + x.systemLanguage); document.write("<br />"); document.write("UserLanguage=" + x.userLanguage);