4.htm

javascript book

      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">其中</font></span><font size="3"><span lang="EN-US">university</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是一个已经存在的对象，</span><span lang="EN-US">Name</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、</span><span lang="EN-US">City</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、</span><span lang="EN-US">Date</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是它的三个属性，并通过操作对其赋值。</span></font></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">（２）通过对象的下标实现引用</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">university[0]=“</font></span><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">云南</span><span lang="EN-US">”</span></font></p> 
      <p style="line-height: 150%"><font size="3"><span lang="EN-US">university[1]=“</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">昆明市</span><span lang="EN-US">”</span></font></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">university[2]=&quot;1999&quot;</font></span></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">通过数组形式的访问属性，可以使用循环操作获取其值。</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">function   
      showunievsity(object)</font></span></p>  
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">for (var j=0;j&lt;2; j++)</font></span></p>  
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">document.write(object[j])</font></span></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">若采用</font></span><font size="3"><span lang="EN-US">For...in</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">则可以不知其属性的个数后就可以实现：</span></font></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">Function showmy(object)</font></span></p>  
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">for (var prop in this)</font></span></p>  
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">docament.write(this[prop]);</font></span></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">（３）通过字符串的形式实现</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">university[&quot;Name&quot;]=“</font></span><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">云南</span><span lang="EN-US">”</span></font></p> 
      <p style="line-height: 150%"><font size="3"><span lang="EN-US">university[&quot;City&quot;]=“</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">昆明市</span><span lang="EN-US">”</span></font></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">university[&quot;Date&quot;]=&quot;1999&quot;</font></span></p> 
      <p style="line-height: 150%"><b><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">　</font></span><font size="3"><span lang="EN-US"><o:p>
      </o:p>
      </span></font></b></p>
      <p style="line-height: 150%"><b><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">５、对象的方法的引用</span><span lang="EN-US"><o:p>
      </o:p>
      </span></font></b></p>
      <p style="line-height: 150%"><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在</span><span lang="EN-US">JavaScript</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中对象方法的引用是非常简单的。</span></font></p>
      <p style="line-height: 150%; margin-left: 72pt"><span lang="EN-US"><font size="3">ObjectName.methods()</font></span></p>
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">实际上</font></span><font size="3"><span lang="EN-US">methods()=FunctionName</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法实质上是一个函数。</span> 
      <span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">如引用</span><span lang="EN-US">university</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对象中的</span><span lang="EN-US">showmy</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（）方法，则可使用：</span></font></p>  
      <p style="line-height: 150%; margin-left: 72pt"><span lang="EN-US"><font size="3">document.write   
      (university.showmy())</font></span></p>  
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">或：</font></span><font size="3"><span lang="EN-US">document.write(university)</span></font></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">如引用</font></span><font size="3"><span lang="EN-US">math</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">内部对象中</span><span lang="EN-US">cos()</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的方法</span></font></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">则：</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">with(math)</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">document.write(cos(35));</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">document.write(cos(80));</font></span></p> 
      <p style="line-height: 150%"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">若不使用</font></span><font size="3"><span lang="EN-US">with</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">则引用时相对要复杂些：</span></font></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">document.write(Math.cos(35))</font></span></p> 
      <p style="line-height: 150%"><span lang="EN-US"><font size="3">document.write(math.sin(80))</font></span></p> 
      <p style="line-height: 150%"><b><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><font size="3">　</font></span><font size="3"><span lang="EN-US"><o:p>
      </o:p>
      </span></font></b></p>
      <p style="line-height: 150%"><b><font size="3"><span style="font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">二、常用对象的属性和方法</span><span lang="EN-US" style="FONT-SIZE: 18pt"><o:p>
      </o:p>
      </span></font></b></p>
      <p style="line-height: 150%"><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">　　</span><span lang="EN-US">JavaScript</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">为我们提供了一些非常有用的常用内部对象和方法。用户不需要用脚本来实现这些功能。这正是基于对象编程的真正目的。</span></font></p>
      <p style="line-height: 150%"><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">　　在</span><span lang="EN-US">JavaScript</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">提供了</span><span lang="EN-US">string</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（字符串）、</span><span lang="EN-US">math</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（数值计算）和</span><span lang="EN-US">Date</span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（日期）三种对象和其它一些相关的方法。从而为编程人员快速开发强大的脚本程序提供了非常有利的条件。</span></font></p>
      <p style="line-height: 150%; margin-left: 36pt"><b><span lang="EN-US"><font size="3">1</font></span><font size="3"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、常用内部对象</span><span lang="EN-US"><o:p>
      </o:p>
      </span></font></b></p>