JS数组操作之pop, push, unshift, splice, shift

在JavaScript编程中，数组是重要的数据结构之一。这里将讲解JS中常用的5种数组操作方法——pop, push, unshift, shift和 splice。

1. pop

pop()方法是用于移除并返回数组中的最后一个元素。它会改变原始的数组。

语法：

arr.pop()

示例1：

var fruits = ["apple", "banana", "orange"];
var poppedFruit = fruits.pop();

// 输出：poppedFruit: "orange", fruits: ["apple", "banana"]
console.log(`poppedFruit: ${poppedFruit}, fruits: ${fruits}`);

示例2：

var emptyArr = [];
var poppedItem = emptyArr.pop();

// 输出：poppedItem: undefined, emptyArr: []
console.log(`poppedItem: ${poppedItem}, emptyArr: ${emptyArr}`);

2. push

push()方法是用于向数组的末尾添加一个或多个元素。它也会改变原始的数组。

语法：

arr.push(element1, ..., elementN);

示例1：

var fruits = ["apple", "banana"];
var newLength = fruits.push("orange", "kiwi");

// 输出：newLength: 4, fruits: ["apple", "banana", "orange", "kiwi"]
console.log(`newLength: ${newLength}, fruits: ${fruits}`);

示例2：

var emptyArr = [];
var newLength = emptyArr.push(5);

// 输出：newLength: 1, emptyArr: [5]
console.log(`newLength: ${newLength}, emptyArr: ${emptyArr}`);

3. unshift

unshift()方法是用于向数组的开头添加一个或多个元素。它也会改变原始的数组。

语法：

arr.unshift(element1, ..., element);

示例1：

var fruits = ["orange", "kiwi"];
var newLength = fruits.unshift("apple", "banana");

// 输出：newLength: 4, fruits: ["apple", "banana", "orange", "kiwi"]
console.log(`newLength: ${newLength}, fruits: ${fruits}`);

示例2：

var emptyArr = [];
var newLength = emptyArr.unshift(5);

// 输出：newLength: 1, emptyArr: [5]
console.log(`newLength: ${newLength}, emptyArr: ${emptyArr}`);

4. splice

splice()方法可以用于添加或删除数组中的元素。它也会改变原始的数组。

语法：

arr.splice(start[, deleteCount[, element1[, ...[, elementN]]]])

• start：要修改的数组的开始索引
• deleteCount：要删除的元素个数。如果设置为0，则不删除元素
• element1, ..., elementN：要添加到数组中的元素

示例1：删除元素

var fruits = ["apple", "banana", "orange", "kiwi"];
var deletedFruits = fruits.splice(1, 2);

// 输出：deletedFruits: ["banana", "orange"], fruits: ["apple", "kiwi"]
console.log(`deletedFruits: ${deletedFruits}, fruits: ${fruits}`);

示例2：添加元素

var fruits = ["apple", "kiwi"];
var newFruits = fruits.splice(1, 0, "banana", "orange");

// 输出：newFruits: [], fruits: ["apple", "banana", "orange", "kiwi"]
console.log(`newFruits: ${newFruits}, fruits: ${fruits}`);

5. shift

shift()方法是用于移除并返回数组的第一个元素。它也会改变原始的数组。

语法：

arr.shift()

示例1：

var fruits = ["apple", "banana", "orange"];
var shiftedFruit = fruits.shift();

// 输出：shiftedFruit: "apple", fruits: ["banana", "orange"]
console.log(`shiftedFruit: ${shiftedFruit}, fruits: ${fruits}`);

示例2：

var emptyArr = [];
var shiftedItem = emptyArr.shift();

// 输出：shiftedItem: undefined, emptyArr: []
console.log(`shiftedItem: ${shiftedItem}, emptyArr: ${emptyArr}`);

以上就是JS数组操作之pop, push, unshift, splice, shift的完整攻略。希望能对您有所帮助！