js面向对象写法及栈的实现

function Stack() {
  this.dataStore = [];
  this.top = 0; //指向栈顶的位置
  this.push = push;
  this.pop = pop;
  this.peek = peek;
  this.clear = clear;
  this.length = length;
  
  function push(element) {
    this.dataStore[this.top++] = element; //先赋值后++
  }
  
  function peek() {
    return this.dataStore[this.top - 1];
  }

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

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

  function length() {
    return this.top;
  }
}

var s = new Stack(); 
s.push("David"); 
s.push("Raymond"); 
s.push("Bryan"); 
console.log(s);
console.log("length: " + s.length()); 

 

注意：

这样的一步操作arr[i++]="ddd";----》这里的执行顺序是：先执行赋值后进行的++运算

等价于下面的两布操作：

arr[i] = "ddd";

i++;

 

 

//这样写才是先执行++运算

arr[++i]="ddd";