JavaScript 高性能数组去重的方法

// distinct.js
let arr1 = Array.from(new Array(100000), (x, index)=>{
 return index
})
let arr2 = Array.from(new Array(50000), (x, index)=>{
 return index+index
})
let start = new Date().getTime()
console.log('开始数组去重')
function distinct(a, b) {
 // 数组去重
}
console.log('去重后的长度', distinct(arr1, arr2).length)
let end = new Date().getTime()
console.log('耗时', end - start)

function distinct(a, b) {
 let arr = a.concat(b);
 return arr.filter((item, index)=> {
 return arr.indexOf(item) === index
 })
}

function distinct(a, b) {
 let arr = a.concat(b);
 for (let i=0, len=arr.length; i<len; i++) {
 for (let j=i+1; j<len; j++) {
  if (arr[i] == arr[j]) {
  arr.splice(j, 1);
  // splice 会改变数组长度，所以要将数组长度 len 和下标 j 减一
  len--;
  j--;
  }
 }
 }
 return arr
}

function distinct(a, b) {
 let arr = a.concat(b)
 let result = []
 for (let i of arr) {
 !result.includes(i) && result.push(i)
 }
 return result
}

function distinct(a, b) {
 let arr = a.concat(b)
 arr = arr.sort()
 let result = [arr[0]]
 for (let i=1, len=arr.length; i<len; i++) {
 arr[i] !== arr[i-1] && result.push(arr[i])
 }
 return result
}

function distinct(a, b) {
 return Array.from(new Set([...a, ...b]))
}

function distinct(a, b) {
 let arr = a.concat(b)
 let result = []
 let obj = {}
 for (let i of arr) {
 if (!obj[i]) {
  result.push(i)
  obj[i] = 1
 }
 }
 return result
}