# 数组去重
# Map 去重（效率最快）
const arr = [1, 1, 4, 3, 2, 6];
const map = new Map();
let newArr = [];
for (let item of arr) {
if (!map.get(item)) {
map.set(item, 1);
newArr.push(item);
}
}
console.log(newArr); // [1, 4, 3, 2, 6]
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# Set 去重（简洁）
const arr = [1, 1, 4, 3, 2, 6];
const set = new Set(arr);
let newArr = [...set]; // 或 let newArr = Array.from(set);
console.log(newArr); // [1, 4, 3, 2, 6]
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# Array.prototype.indexOf() 去重
const arr = [1, 1, 4, 3, 2, 6];
// 方法一：
let newArr = arr.filter((item, index) => {
return arr.indexOf(item) === index;
});
console.log(newArr); // [1, 4, 3, 2, 6]
// 方法二：
let newArr = [];
for (let item of arr) {
if (newArr.indexOf(item) === -1) {
newArr.push(item);
}
}
console.log(newArr); // [1, 4, 3, 2, 6]
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# Array.prototype.includes() 去重
const arr = [1, 1, 4, 3, 2, 6];
let newArr = [];
arr.forEach(item => {
if (!newArr.includes(item)) {
newArr.push(item);
}
});
console.log(newArr); // [1, 4, 3, 2, 6]
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# Array.prototype.sort() 去重
const arr = [1, 1, 4, 3, 2, 6];
arr = arr.sort();
arr.forEach((item, index) => {
if (arr[index] !== arr[index + 1]) {
newArr.push(arr[index]);
}
});
console.log(newArr); // [1, 2, 3, 4, 6]
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# for 循环 去重
const arr = [1, 1, 4, 3, 2, 6];
let newArr = [];
for (let i = 0; i < arr.length; i++) {
for (let j = i + 1; j < arr.length; j++) {
if (arr[i] === arr[j]) {
j = ++i;
}
}
newArr.push(arr[i]);
}
console.log(newArr); // [1, 4, 3, 2, 6]
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And So On ...