栈是一种常见的数据结构，常用于app页面堆栈、括号匹配校验、中缀表达式转换、图的深度优先遍历等场景，本文参考java jdk源码，在JavaScript中实现这种数据结构。
栈是限定仅在表尾进行插入和删除操作的线性表。允许插入和删除的一端称为栈顶（top），另一端称为栈底（bottom）,不含任何数据元素的栈称为空栈。栈又称为后进先出的线性表
参考[java的Stack源码](# 四、附:java的Stack源码)，我们通过定义JavaScript栈的基本方法：
入栈(push)
出栈(pop)
返回栈顶元素值(peek)
判断堆栈是否为空(empty)
返回给定对象的位置(search)
清空栈(clear) 等
并实现JavaScript源码如下
// 定义堆栈类
class Stack {
constructor() {
this._elementData = [];
}
// 入栈
push(item) {
this._elementData[this._elementData.length] = item;
}
// 出栈
pop() {
if (this._elementData.length) {
this._elementData.splice(this._elementData.length - 1, 1);
return true;
} else {
return false;
}
}
// 返回栈顶元素值,若堆栈为空则返回null
peek() {
if (this._elementData.length) {
return this._elementData[this._elementData.length - 1];
} else {
return null;
}
}
// 判断堆栈是否为空
empty() {
return this._elementData.length === 0;
}
// 返回给定对象的位置
search(item) {
let i = this._elementData.lastIndexOf(item);
if (i >= 0) {
return this.size() - i;
} else {
return -1;
}
}
// 获取堆栈元素个数
size() {
return this._elementData.length;
}
// 获取堆栈数据
getData() {
return this._elementData;
}
// 清空栈
clear() {
this._elementData = [];
}
}
const stack = new Stack();
stack.push('nodeA');
stack.push('nodeB');
stack.push('nodeC');
while (!stack.empty()) {
console.log(stack.getData());
stack.pop();
}
验证结果
调用java的Stack
public class StackTest {
public static void main(String[] args) {
Stack<String> stack = new Stack<String>();
stack.push("nodeA");
stack.push("nodeB");
stack.push("nodeC");
while (!stack.isEmpty()){
System.out.println(stack);
stack.pop();
}
}
}
java的Stack源码：
/*
* Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.util;
/**
* The <code>Stack</code> class represents a last-in-first-out
* (LIFO) stack of objects. It extends class <tt>Vector</tt> with five
* operations that allow a vector to be treated as a stack. The usual
* <tt>push</tt> and <tt>pop</tt> operations are provided, as well as a
* method to <tt>peek</tt> at the top item on the stack, a method to test
* for whether the stack is <tt>empty</tt>, and a method to <tt>search</tt>
* the stack for an item and discover how far it is from the top.
* <p>
* When a stack is first created, it contains no items.
*
* <p>A more complete and consistent set of LIFO stack operations is
* provided by the {@link Deque} interface and its implementations, which
* should be used in preference to this class. For example:
* <pre> {@code
* Deque<Integer> stack = new ArrayDeque<Integer>();}</pre>
*
* @author Jonathan Payne
* @since JDK1.0
*/
public
class Stack<E> extends Vector<E> {
/**
* Creates an empty Stack.
*/
public Stack() {
}
/**
* Pushes an item onto the top of this stack. This has exactly
* the same effect as:
* <blockquote><pre>
* addElement(item)</pre></blockquote>
*
* @param item the item to be pushed onto this stack.
* @return the <code>item</code> argument.
* @see java.util.Vector#addElement
*/
public E push(E item) {
addElement(item);
return item;
}
/**
* Removes the object at the top of this stack and returns that
* object as the value of this function.
*
* @return The object at the top of this stack (the last item
* of the <tt>Vector</tt> object).
* @throws EmptyStackException if this stack is empty.
*/
public synchronized E pop() {
E obj;
int len = size();
obj = peek();
removeElementAt(len - 1);
return obj;
}
/**
* Looks at the object at the top of this stack without removing it
* from the stack.
*
* @return the object at the top of this stack (the last item
* of the <tt>Vector</tt> object).
* @throws EmptyStackException if this stack is empty.
*/
public synchronized E peek() {
int len = size();
if (len == 0)
throw new EmptyStackException();
return elementAt(len - 1);
}
/**
* Tests if this stack is empty.
*
* @return <code>true</code> if and only if this stack contains
* no items; <code>false</code> otherwise.
*/
public boolean empty() {
return size() == 0;
}
/**
* Returns the 1-based position where an object is on this stack.
* If the object <tt>o</tt> occurs as an item in this stack, this
* method returns the distance from the top of the stack of the
* occurrence nearest the top of the stack; the topmost item on the
* stack is considered to be at distance <tt>1</tt>. The <tt>equals</tt>
* method is used to compare <tt>o</tt> to the
* items in this stack.
*
* @param o the desired object.
* @return the 1-based position from the top of the stack where
* the object is located; the return value <code>-1</code>
* indicates that the object is not on the stack.
*/
public synchronized int search(Object o) {
int i = lastIndexOf(o);
if (i >= 0) {
return size() - i;
}
return -1;
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = 1224463164541339165L;
}