用js实现一个栈

function Stack() {
  this.dataStore = [];
  this.top = 0;//栈顶元素的位置
  this.push = push;
  this.pop = pop;
  this.peek = peek;
  this.length=length;
  this.clear=clear;
}

function push(element) {//进栈
   this.dataStore[this.top++] = element;
}

function pop() {//出栈
  return this.dataStore[--this.top];
}

function peek() {//栈顶元素
  return this.dataStore[this.top-1];
}

function length() {
  return this.top;
}

function clear() {
  this.top = 0;
}

//测试栈的实现
var s= new Stack();
s.push("D");
s.push("R");
s.push("B");
console.log(s.length());
console.log(s.peek());
console.log(s.clear());
console.log(s.length());

栈的应用：
(1)数制之间转换

function mulBase(num,base) {
  var s = new Stack();
  do{
    s.push(num%base);
    num = Math.floor(num/base);
  }while(num>0);
  var converted = "";
  while(s.length()>0){
    converted+=s.pop();
  }
  return converted;
}
console.log(mulBase(125,8));//输出175

(2)判断回文字符串

function isPalindrome(word) {
  var s = new Stack();
  for (var i = 0; i < word.length; i++) {
    s.push(word[i]);
  }
  var newStr = "";
  while (s.length() > 0) {
    newStr += s.pop();
  }
  if(word === newStr){
    return true;
  }
  return false;
}

(3)使用栈实现递归