从函数声明的堆栈访问变量
从函数声明的堆栈访问变量
提问于 2018-09-12 06:50:23
在使用函数风格而不是原型或伪经典风格为JavaScript创建堆栈接口时，下面的“存储”和“计数”变量是否应该分别为someInstance.storage和someInstance.count，以便稍后可以在此堆栈的实例上访问它们？
随着变量的声明，一旦我们通过执行函数创建了堆栈的实例，我们就失去了查看计数(大小)和存储(堆栈中的属性)的权限。
声明我们稍后需要使用函数式创建模式访问的属性(而不是方法)的最佳方法是什么？
谢谢!
var Stack = function(){
var someInstance = {};
var storage = {};
var count = 0;
someInstance.push = function(value){
storage[count++] = value;
};
someInstance.pop = function(){
if(count){
var popped = storage[--count];
}
delete storage[count];
return popped;
};
someInstance.size = function(){
return count;
};
return someInstance;
};
var stack = Stack();回答 3
Stack Overflow用户
发布于 2018-09-12 06:55:08
下面提到的私有变量可以在closure的javascript中研究。
参考：https://developer.mozilla.org/ko/docs/Web/JavaScript/Guide/Closures
var Stack = function(){
// PUBLIC
var someInstance = {};
// PRIVATE: Attach _ to private variables. (just implicit rule.)
var _storage = {};
var _count = 0;
someInstance.push = function(value){
storage[_count++] = value;
};
someInstance.pop = function(){
if(_count){
var popped = storage[--_count];
}
delete storage[_count];
return popped;
};
someInstance._size = function(){
return _count;
};
// if you assign public variable, you can access!!!
someInstance.size = _size;
someInstance.count = _count;
return someInstance;
};
var stack = Stack();Stack Overflow用户
发布于 2018-09-12 14:47:41
var Stack = function(){
let storage = [], count = 0; // these will be caputured as a closure
return {
// the returned object will have push, pop, and a count getter
push(v) { //method
storage.push(v)
count++
},
pop: function() {
if (count) count--
return storage.pop()
},
get count(){ // allow reading of count
return count
},
get insidebox(){ // allow reading of count
return storage
},
callprice:function(cnt){
var price=cnt*100;
return price;
}
}
}
Stack.prototype.price2 = function() {
return "testpr";
};
var sb = Stack();
console.log(sb.count);
sb.push('paint');
console.log(sb.insidebox);
console.log(sb.count);
sb.push('Sharee');
console.log(sb.insidebox);
sb.push('Shirt');
sb.push('shoes');
console.log(sb.insidebox);
sb.pop();
console.log(sb.insidebox);
console.log(sb.count);
console.log(sb.callprice(sb.count));
Stack Overflow用户
发布于 2018-09-12 14:57:25
function Person(first, last, age, eye) {
this.firstName = first;
this.lastName = last;
this.age = age;
this.eyeColor = eye;
}
Person.prototype.nationlity='Indian';
Person.prototype.fullname = function() {
return this.firstName + " " + this.lastName
};
var myFather = new Person("Lalji", "Maurya", 50, "blue");
console.log(myFather.fullname());
console.log(myFather);
console.log(myFather.nationlity);
var myBrother = new Person("Ashish", "Maurya", 28, "black");
console.log(myBrother.fullname());
console.log(myBrother);
console.log(myBrother.nationlity);
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/52285157
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