02 深入理解function&构造函数
2019-01-08 本文已影响0人
陈柯梦
function&构造函数
演示代码
<html>
<body>
<script type="text/javascript">
"use strict"
// 通过构造函数 创建类(object)属性
function fucConstruction(x){
this.obj = x;
console.log(`fucConstruction this.obj====>${this.obj}`);
}
fucConstruction.prototype.rootobj = "rootobj";
var a = new fucConstruction('obj');
console.log(`obj is a property====>${a.hasOwnProperty('obj')}`);
console.log(`obj is fucConstruction property====>${fucConstruction.prototype.hasOwnProperty('obj')}`);
console.log(`rootobj is a property====>${a.hasOwnProperty('rootobj')}`);
console.log(`rootobj is fucConstruction property====>${fucConstruction.prototype.hasOwnProperty('rootobj')}`);
console.log(`a is ====>${typeof a}`);
// 函数受返回值影响
function fucReturnObject(x){
this.obj = x;
console.log(`fucReturnObject this.obj====>${this.obj}`);
return {};
}
var b = new fucReturnObject('obj');
console.log(`obj is b property====>${b.hasOwnProperty('obj')}`);
console.log(`obj is fucReturnObject property====>${fucReturnObject.prototype.hasOwnProperty('obj')}`);
console.log(`b is ====>${typeof b}`);
function fucReturnNull(x){
this.obj = x;
console.log(`fucReturnNull this.obj====>${this.obj}`);
return null;
}
var c = new fucReturnNull('obj');
console.log(`obj is c property====>${c.hasOwnProperty('obj')}`);
console.log(`obj is fucReturnNull property====>${fucReturnNull.prototype.hasOwnProperty('obj')}`);
console.log(`c is ====>${typeof c}`);
function fucReturnFunc(x){
this.obj = x;
console.log(`fucReturnFunc this.obj====>${this.obj}`);
return function(){};
}
var d = new fucReturnFunc('obj');
console.log(`obj is d property====>${d.hasOwnProperty('obj')}`);
console.log(`obj is fucReturnFunc property====>${fucReturnFunc.prototype.hasOwnProperty('obj')}`);
console.log(`d is ====>${typeof d}`);
</script>
</body>
</html>
通过构造函数 创建类(object)属性
function fucConstruction(x){
this.obj = x;
console.log(`fucConstruction this.obj====>${this.obj}`);
}
fucConstruction.prototype.rootobj = "rootobj";
var a = new fucConstruction('obj');
console.log(`obj is a property====>${a.hasOwnProperty('obj')}`);
console.log(`obj is fucConstruction property====>${fucConstruction.prototype.hasOwnProperty('obj')}`);
console.log(`rootobj is a property====>${a.hasOwnProperty('rootobj')}`);
console.log(`rootobj is fucConstruction property====>${fucConstruction.prototype.hasOwnProperty('rootobj')}`);
console.log(`a is ====>${typeof a}`);
构造函数创建的属性属于新类的属性，不被函数原型继承
函数受返回值影响
function fucReturnObject(x){
this.obj = x;
console.log(`fucReturnObject this.obj====>${this.obj}`);
return {};
}
var b = new fucReturnObject('obj');
console.log(`obj is b property====>${b.hasOwnProperty('obj')}`);
console.log(`obj is fucReturnObject property====>${fucReturnObject.prototype.hasOwnProperty('obj')}`);
console.log(`b is ====>${typeof b}`);
function fucReturnNull(x){
this.obj = x;
console.log(`fucReturnNull this.obj====>${this.obj}`);
return null;
}
var c = new fucReturnNull('obj');
console.log(`obj is c property====>${c.hasOwnProperty('obj')}`);
console.log(`obj is fucReturnNull property====>${fucReturnNull.prototype.hasOwnProperty('obj')}`);
console.log(`c is ====>${typeof c}`);
function fucReturnFunc(x){
this.obj = x;
console.log(`fucReturnFunc this.obj====>${this.obj}`);
return function(){};
}
var d = new fucReturnFunc('obj');
console.log(`obj is d property====>${d.hasOwnProperty('obj')}`);
console.log(`obj is fucReturnFunc property====>${fucReturnFunc.prototype.hasOwnProperty('obj')}`);
console.log(`d is ====>${typeof d}`);
函数构造受返回值影响，如果有返回值，则以return结果为准，即"无返回则返回函数构造对象，否则指针后移至新的返回对象"
