利用 ES6 Set 去重
function unique(arr) {
return Array.from(new Set(arr))
}
let arr = [1, 2, 3, 4, 5, 1, 2, 3]
console.log(unique(arr))
// [1, 2, 3, 4, 5]
利用当前项和剩余项比较去重
方法较多,这里用比较典型的indexOf()
方法
function unique(arr) {
let newArr = []
for (let i = 0; i < arr.length; i++) {
let current = arr[i]
let residue = arr.slice(i + 1)
if (residue.indexOf(current) === -1) {
newArr.push(current)
}
}
return newArr
}
let arr = [1, 2, 3, 4, 5, 1, 2, 3]
console.log(unique(arr))
// [4, 5, 1, 2, 3]
先排序,再进行遍历及相邻元素比对去重
function unique(arr) {
arr.sort((a, b) => a - b)
let newArr = [arr[0]]
for (let i = 1; i < arr.length; i++) {
if (arr[i] !== arr[i - 1]) {
newArr.push(arr[i])
}
}
return newArr
}
let arr = [1, 2, 3, 4, 5, 1, 2, 3]
console.log(unique(arr))
// [4, 5, 1, 2, 3]
利用对象的属性不能相同的特点进行去重
function unique(arr) {
let obj = {}
let newArr = []
for (let i = 0; i < arr.length; i++) {
current = arr[i]
if (!obj[current]) {
obj[current] = 1
newArr.push(current)
}
}
return newArr
}
let arr = [1, 2, 3, 4, 5, 1, 2, 3]
console.log(unique(arr))
// [1, 2, 3, 4, 5]