我正在学习一个库，看到一个示例，但我不明白它是如何完成的？ 在类的函数中，“this”变量包含该类的所有方法。 外部只有公共(public)方法可用。
protected 方法更有趣。它们仅在继承类中可用。 它是如何工作的？
请参阅以下文档中的示例:
/**
* A-class
*/
var ClassA = AWeb.class({
public : {
/**
* A-class constructor
*/
constructor : function() {
/* Private variable */
this.variable1 = "A";
this.calls = 0;
},
/**
* Function returns information about the object
*/
getInfo : function() {
this.incCalls();
return "variable1=" + this.variable1 + ", calls=" + this.calls;
}
},
protected : {
/**
* Protected function
*/
changeVariable1 : function( value ) {
this.variable1 = value;
}
},
private : {
/**
* Private function
*/
incCalls : function() {
this.calls++;
}
}
});
/**
* C-class
*/
var ClassC = AWeb.class({
extends : ClassA,
public : {
/**
* B-class constructor
*/
constructor : function() {
this.super();
this.changeVariable1( "C" );
},
/**
* Function returns extended information about the object
*/
getLongInfo : function() {
return this.incCalls !== undefined ? "incCalls visible" : "incCalls undefined";
}
}
});
/**
* Main project function
*/
function main() {
var a = new ClassA(),
c = new ClassC();
alert(
"a instanceof ClassA: " + (a instanceof ClassA) + "\n" +
"a instanceof ClassC: " + (a instanceof ClassC) + "\n" +
"a.getInfo " + (a.getInfo ? "exists" : "undefined") + "\n" +
"a.getLongInfo " + (a.getLongInfo ? "exists" : "undefined") + "\n" +
"a.changeVariable1 " + (a.changeVariable1 ? "exists" : "undefined") + "\n" +
"a.getInfo()=" + a.getInfo() + "\n\n" +
"c instanceof ClassA: " + (c instanceof ClassA) + "\n" +
"c instanceof ClassC: " + (c instanceof ClassC) + "\n" +
"c.getInfo " + (c.getInfo ? "exists" : "undefined") + "\n" +
"c.getLongInfo " + (c.getLongInfo ? "exists" : "undefined") + "\n" +
"c.changeVariable1 " + (c.changeVariable1 ? "exists" : "undefined") + "\n" +
"c.getInfo()=" + c.getInfo() + "\n" +
"c.getLongInfo()=" + c.getLongInfo()
);
}
最佳答案
很抱歉这个问题不准确。我知道javascript中继承的原理。 我对指定库中继承的实现感兴趣。有效，我测试过。
图书馆是免费的，但它有封闭代码，无法阅读。 它适用于所有浏览器。
我将指定的代码包装到了html页面中，请查看。
<!DOCTYPE HTML>
<html>
<head>
<title>Sample project</title>
<!-- Styles -->
<link rel="stylesheet" type="text/css" href="http://a-web.me/styles/default/a-web.css" >
<!-- Scripts -->
<script type="text/javascript" src="http://a-web.me/scripts/a-web.js"></script>
</head>
<body>
<script type="text/javascript">
/**
* A-class
*/
var ClassA = AWeb.class({
public : {
/**
* A-class constructor
*/
constructor : function() {
/* Private variable */
this.variable1 = "A";
this.calls = 0;
},
/**
* Function returns information about the object
*/
getInfo : function() {
this.incCalls();
return "variable1=" + this.variable1 + ", calls=" + this.calls;
}
},
protected : {
/**
* Protected function
*/
changeVariable1 : function( value ) {
this.variable1 = value;
}
},
private : {
/**
* Private function
*/
incCalls : function() {
this.calls++;
}
}
});
/**
* C-class
*/
var ClassC = AWeb.class({
extends : ClassA,
public : {
/**
* B-class constructor
*/
constructor : function() {
this.super();
this.changeVariable1( "C" );
},
/**
* Function returns extended information about the object
*/
getLongInfo : function() {
return this.incCalls !== undefined ? "incCalls visible" : "incCalls undefined";
}
}
});
/**
* Main project function
*/
function main() {
var a = new ClassA(),
c = new ClassC();
alert(
"a instanceof ClassA: " + (a instanceof ClassA) + "\n" +
"a instanceof ClassC: " + (a instanceof ClassC) + "\n" +
"a.getInfo " + (a.getInfo ? "exists" : "undefined") + "\n" +
"a.getLongInfo " + (a.getLongInfo ? "exists" : "undefined") + "\n" +
"a.changeVariable1 " + (a.changeVariable1 ? "exists" : "undefined") + "\n" +
"a.getInfo()=" + a.getInfo() + "\n\n" +
"c instanceof ClassA: " + (c instanceof ClassA) + "\n" +
"c instanceof ClassC: " + (c instanceof ClassC) + "\n" +
"c.getInfo " + (c.getInfo ? "exists" : "undefined") + "\n" +
"c.getLongInfo " + (c.getLongInfo ? "exists" : "undefined") + "\n" +
"c.changeVariable1 " + (c.changeVariable1 ? "exists" : "undefined") + "\n" +
"c.getInfo()=" + c.getInfo() + "\n" +
"c.getLongInfo()=" + c.getLongInfo()
);
}
</script>
</body>
</html>
关于inheritance - 类方法在javascript中是如何实现的？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18817066/