栈特点
入栈出栈速度很快，先进后出，能用递归实现的场景，都能使用迭代加栈来实现
构造栈
JS中的数组同时具备栈和队列的特性
function Stack() {
this.dataStore = [];
this.length = 0;
this.top = 0;
}
Stack.prototype = {
push(data) {
this.dataStore[this.top++] = data;
this.length++;
},
pop() {
if (this.top === 0) {
return undefined;
}
this.length--;
return this.dataStore[--this.top];
},
peek() {
return this.dataStore[this.top - 1];
},
clear() {
this.top = 0;
}
}
测试
var s = new Stack();
s.push(1);
s.push(2);
s.pop();
s.push(3);
console.log(s.length);
console.log(s.peek());
s.clear();
console.log(s.peek());
