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javascript设计模式学习笔记

2024-07-19 19:08:52   226人阅读

1、有一些比较常用的代码可以作为积累，这样在实现某个功能的时候能更快的达到目的，学习基础是为了看懂，但是要能应用除了自己写，也应该积累比较好的代码：

逐步尝试每一种XHR对象，直到遇到当前的javascript环境支持的对象为止。

/ 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.‘);
  }
}

}

})();

2、关于获取当前浏览器信息的常用方法：
//=========
var browser=navigator.appName
var b_version=navigator.appVersion
var version=parseFloat(b_version)
document.write(“浏览器名称：“+ browser)
document.write(“
“)
document.write(“浏览器版本：“+ version)
//============
document.write(“

代码：“)
document.write(navigator.appCodeName + “

“)

document.write(“

平台：“)
document.write(navigator.platform + “

“)

document.write(“

Cookies 启用：“)
document.write(navigator.cookieEnabled + “

“)

document.write(“

浏览器的用户代理报头：“)
document.write(navigator.userAgent + “

“)

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

javascript设计模式学习笔记


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