javascript - JS 实现栈时clear方法不清楚

Question

我最近在看这本书chapter ，其中解释了如何在 JS 中创建堆栈。这是代码:

function Stack() {
   this.dataStore = [];
   this.top = 0;
   this.push = push;
   this.pop = pop;
   this.peek = peek;
   this.clear = clear;
   this.length = length;
}

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

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

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

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

function length() {
   return this.top;
}

我无法理解 clear() 方法。为什么将 top 设置为 0 会清除数组？我也期待着 this.dataStore.length = 0 行。似乎将 top 设置为 0 只会更改指针，而 dataStore 不会改变，这意味着进一步的操作只会覆盖以前的 dataStore 值。谁能解释一下发生了什么事吗？谢谢!

Answer 1

It seems like setting the top to 0 only changes the pointer and the dataStore is unchanged, meaning that further operations would just overwrite the previous dataStore values.

你说得完全正确。我同意这种行为可能是不可取的。

相反，我建议如下:

function Stack() {
   this.dataStore = [];
}
Object.assign(Stack.prototype, {
  push: function(element) {
    this.dataStore.push(element);
  },
  peek: function() {
    return this.dataStore[this.dataStore.length-1];
  },
  pop: function() {
    return this.dataStore.pop();
  },
  clear: function() {
    this.dataStore.length = 0;
  },
  length: function() {
    return this.dataStore.length;
  }
});