function Stack() {
  var items = [];
  this.push = function (ele) {
    items.push(ele);
  };//推栈
  this.pop = function () {
    return items.pop();
  };//弹栈
  this.peek = function () {
    return items[items.length - 1];
  };//查看栈顶元素
  this.isEmpty = function () {
    return items.length === 0;
  };//判断栈是否为空
  this.size = function () {
    return items.length;
  };//栈大小
  this.clear = function () {
    items = [];
  };//清空栈
  this.print = function () {
    console.log(items.toString());
  };//打印栈
}
var stack = new Stack(); //声明栈的实例

function convertBinary(decNum) {  //十进制转换为二进制
  var remStack = new Stack(),
    rem,
    binaryStr = '';
  while(decNum) {
    rem = Math.floor(decNum % 2);
    decNum = Math.floor(decNum / 2);
    remStack.push(rem);   //余数放到栈中
  }
  while(!remStack.isEmpty()) {
    binaryStr += remStack.pop();  //利用pop把栈内元素逐一弹出，将余数拼接成为一个字符串
  }
  return binaryStr;
}
console.log(convertBinary(50));//输出10010

function baseConverter(decNum, base) { //十进制转换为任意进制    
  var base = (base >= 2 && base <= 16) ? base : 10,
    remStack = new Stack(),
    rem,
    baseStr = '',
    digits = '0123456789ABCDEF';
  while(decNum) {
    rem = Math.floor(decNum % base);
    decNum = Math.floor(decNum / base);
    remStack.push(rem);   //余数放到栈中
  }
  while(!remStack.isEmpty()) {
    baseStr += digits[remStack.pop()]; //利用pop把栈内元素逐一弹出，将余数拼接成为一个字符串
  }
  return baseStr;
}