Javascript 自定义类型方法小结

function UserObject(parameter) {
}

<script type="text/javascript">
function userobject(parameter){
}
//myobject is now an object of type userobject!
var myobject=new userobject("hi")
alert(myobject)
</script>

function userobject(parameter){
this.firstproperty=parameter
this.secondproperty="This is the second property"
}

<script>
var myobject=new userobject("hi there.")
//alerts "hi there."
alert(myobject.firstproperty)
//writes "This is the second property"
document.write(myobject.secondproperty)
</script>

//first method function
function computearea(){
var area=this.radius*this.radius*3.14
return area
}
//second method function
function computediameter(){
var diameter=this.radius*2
return diameter
}

<script type="text/javascript">
/*the below creates a new object, and gives it the two methods defined earlier*/
function circle(r){
//property that stores the radius
this.radius=r
this.area=computearea
this.diameter=computediameter
}
</script>

<script type="text/javascript">
var mycircle=new circle(20)
//alerts 1256
alert("area="+mycircle.area())
//alerts 400
alert("diameter="+mycircle.diameter())
</script>