创建对象

qqmmcc123 发表于 2011-12-20 09:48

一.定义对象<div>第一步:创建一个函数来构造新的对象 <div>例:</div><div>命名对象是Card对象,每个对象都有下面的属性:</div><div>--- name(姓名)</div><div>--- addres(地址)</div><div>--- workphone(办公电话)</div><div>--- homephone(家庭电话)</div><div> </div><div>Card对象的构造函数</div><div> </div></div><table border="1" cellspacing="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#999999" width="95%" bgcolor="#F1F1F1"><tbody><tr><td><code>funtion Card(name,address,work,home){ 
    this.name = name; 
    this.address = address; 
    this.workphone = work; 
    this.homephone = home;</code><code>    this.PrictCard = PrictCard;//定义方法引用函数 
}</code></td></tr></tbody></table> <div>二.定义对象的方法(就是定义一个函数)</div><div> </div><div>读取当前对象(this)的属性</div><div> </div><table border="1" cellspacing="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#999999" width="95%" bgcolor="#F1F1F1"><tbody><tr><td><code>function PrictCard(){ 
    line1 = "Name:"+this.name+" \n"; 
    line2 = "Address:"+this.address+" \n"; 
    line3 = "Work Phone:"+this.workphone+" /n"; 
    line4 = "Home Phone:"+this.homephone+" /n"; 
    document.write(line1,line2,line3,line4,"/n"); 
}</code></td></tr></tbody></table><div> </div><div>三.创建对象实例(用new关键字)</div><div> </div><div>tom = new.Card("Tom Jones","123 Elm Street","555-1236","555-9876");</div><div>tom.PrintCard();执行方法</div><div> </div><div>或</div><div> </div><table border="1" cellspacing="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#999999" width="95%" bgcolor="#F1F1F1"><tbody><tr><td><code>holmes = new.Card(); 
holmes.name = "Sherlock Holmes"; 
holmes.address = "221B Baker Street"; 
holmes.workphone = "555-1365"; 
holmes.homephone = "555-5454"; 
 
holmes.Printcard();</code></td></tr></tbody></table> <div><hr>扩展内置对象(扩展内置对象定义的功能,添加新的属性与方法)</div><div>(使用prototype关键字,可以对现有的对象添加属性与方法)</div><div> </div><div>例:向String对象定义添加一个方法创建新的名字heading的方法,将字符串转为HTML标题.</div><div> </div><div>title = "Fred's Home Page";</div><div> </div><div>下面语句将title字符串内容,作为HTML第一级标题:</div><div>documnet.write(title.heading(1));</div><div> </div><div>向String对象添加方法具体如下:</div><div> </div><div> </div>

<table border="1" cellspacing="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#999999" width="95%" bgcolor="#F1F1F1"><tbody><tr><td><code><html> 
<head><title>Test of heading method</title> 
</head> 
<body> 
<script Langage="JavaScript" type="text/Javascript"> 
function addhead(level){ 
    html = "H"+level; 
    text = this.toString(); 
    start = "<"+html+">"; 
    stop = "</"+html+">"; 
    return start+text+stop 
} 
String.prototype.heading = addead; 
document.write("This is a heading 1".heading(1)); 
document.write("This is a heading 2".heading(2)); 
document.write("This is a heading 3".heading(3)); 
</script> 
</body> 
</html></code></td></tr></tbody></table><div> </div><div>定义 addhead()方法,作为新的字符串方法,定义函数后.使用prototype关键字将它添加为String对象的方法,然后,任何String对象都可以使用该方法来.</div>

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创建对象