JavaScript中数组的增删改查操作详解

array.push(element1, element2, ..., elementN);

let fruits = ["apple", "banana"];
fruits.push("orange");  // 向数组末尾添加元素
console.log(fruits); // ["apple", "banana", "orange"]

fruits.push("grape", "mango");  // 可以一次性添加多个元素
console.log(fruits); // ["apple", "banana", "orange", "grape", "mango"]

array.unshift(element1, element2, ..., elementN);

let numbers = [2, 3, 4];
numbers.unshift(1);  // 向数组开头添加元素
console.log(numbers); // [1, 2, 3, 4]

numbers.unshift(-1, 0);  // 向数组开头添加多个元素
console.log(numbers); // [-1, 0, 1, 2, 3, 4]

let removedElement = array.pop();

let fruits = ["apple", "banana", "orange"];
let removed = fruits.pop();  // 删除并返回数组最后一个元素
console.log(fruits); // ["apple", "banana"]
console.log(removed); // "orange"

let removedElement = array.shift();

let numbers = [1, 2, 3];
let removed = numbers.shift();  // 删除并返回数组第一个元素
console.log(numbers); // [2, 3]
console.log(removed); // 1

array.splice(start, deleteCount);

let fruits = ["apple", "banana", "orange", "grape"];
fruits.splice(1, 2);  // 从索引1开始删除2个元素
console.log(fruits); // ["apple", "grape"]

let fruits = ["apple", "banana", "orange"];
fruits.splice(1, 1, "kiwi", "grape");  // 从索引1开始删除1个元素，添加2个新元素
console.log(fruits); // ["apple", "kiwi", "grape", "orange"]

array[index] = newValue;

let fruits = ["apple", "banana", "orange"];
fruits[1] = "kiwi";  // 修改数组中的第二个元素
console.log(fruits); // ["apple", "kiwi", "orange"]

let index = array.indexOf(element);

let fruits = ["apple", "banana", "orange"];
let index = fruits.indexOf("banana");
console.log(index); // 1

let notFound = fruits.indexOf("grape");
console.log(notFound); // -1

let contains = array.includes(element);

let fruits = ["apple", "banana", "orange"];
console.log(fruits.includes("banana")); // true
console.log(fruits.includes("grape"));  // false

let found = array.find(callback);

let numbers = [5, 12, 8, 130, 44];
let found = numbers.find(num => num > 10);
console.log(found); // 12