13个你必须知道的JS数组技巧

1、去重

var fruits = [“banana”, “apple”, “orange”, “watermelon”, “apple”, “orange”, “grape”, “apple”];

// 方法一var uniqueFruits = Array.from(new Set(fruits));console.log(uniqueFruits); // returns [“banana”, “apple”, “orange”, “watermelon”, “grape”]// 方法二var uniqueFruits2 = […new Set(fruits)];console.log(uniqueFruits2); // returns [“banana”, “apple”, “orange”, “watermelon”, “grape”]

2、替换

var fruits = [“banana”, “apple”, “orange”, “watermelon”, “apple”, “orange”, “grape”, “apple”];fruits.splice(0, 2, “potato”, “tomato”);console.log(fruits); // returns [“potato”, “tomato”, “orange”, “watermelon”, “apple”, “orange”, “grape”, “apple”]

3、遍历数组

var friends = [    { name: ‘John’, age: 22 },    { name: ‘Peter’, age: 23 },    { name: ‘Mark’, age: 24 },    { name: ‘Maria’, age: 22 },    { name: ‘Monica’, age: 21 },    { name: ‘Martha’, age: 19 },]
var friendsNames = Array.from(friends, ({name}) => name);console.log(friendsNames); // returns [“John”, “Peter”, “Mark”, “Maria”, “Monica”, “Martha”]

4、清空数组

var fruits = [“banana”, “apple”, “orange”, “watermelon”, “apple”, “orange”, “grape”, “apple”];
fruits.length = 0;console.log(fruits); // returns []

5、数组转换成对象

var fruits = [“banana”, “apple”, “orange”, “watermelon”];var fruitsObj = { …fruits };console.log(fruitsObj); // returns {0: “banana”, 1: “apple”, 2: “orange”, 3: “watermelon”, 4: “apple”, 5: “orange”, 6: “grape”, 7: “apple”}

6、填充数组

var newArray = new Array(10).fill(“1”);console.log(newArray); // returns [“1”, “1”, “1”, “1”, “1”, “1”, “1”, “1”, “1”, “1”, “1”]

7、合并数组

var fruits = [“apple”, “banana”, “orange”];var meat = [“poultry”, “beef”, “fish”];var vegetables = [“potato”, “tomato”, “cucumber”];var food = […fruits, …meat, …vegetables];console.log(food); // [“apple”, “banana”, “orange”, “poultry”, “beef”, “fish”, “potato”, “tomato”, “cucumber”]

8、两个数组的交集

var numOne = [0, 2, 4, 6, 8, 8];var numTwo = [1, 2, 3, 4, 5, 6];var duplicatedValues = […new Set(numOne)].filter(item => numTwo.includes(item));console.log(duplicatedValues); // returns [2, 4, 6]

9、去除假值

var mixedArr = [0, “blue”, “”, NaN, 9, true, undefined, “white”, false];var trueArr = mixedArr.filter(Boolean);console.log(trueArr); // returns [“blue”, 9, true, “white”]

10、随机值

var colors = [“blue”, “white”, “green”, “navy”, “pink”, “purple”, “orange”, “yellow”, “black”, “brown”];var randomColor = colors[(Math.floor(Math.random() * (colors.length)))]

11、倒序

var colors = [“blue”, “white”, “green”, “navy”, “pink”, “purple”, “orange”, “yellow”, “black”, “brown”];var reversedColors = colors.reverse();// 或者 colors.slice().reverse();// 两者有啥区别？console.log(reversedColors); // returns [“brown”, “black”, “yellow”, “orange”, “purple”, “pink”, “navy”, “green”, “white”, “blue”]

12、lastIndexOf()

var nums = [1, 5, 2, 6, 3, 5, 2, 3, 6, 5, 2, 7];var lastIndex = nums.lastIndexOf(5);console.log(lastIndex); // returns 9

13、求和

var nums = [1, 5, 2, 6];var sum = nums.reduce((x, y) => x + y);console.log(sum); // returns 14

总结