javascript数组去重

1. Set方法

const arr = [1, 2, 3, 4, 1, 2, 3, 4]
const arr1 = [...new Set(arr)]
console.log(arr1)

2. reduce方法

const arr = [1, 2, 3, 4, 1, 2, 3, 4]
const arr2 = arr.reduce((prev, cur) => {
    if(!prev.includes(cur)) {
        prev.push(cur)
    }
    return prev
}, [])
console.log(arr2)

3.filter结合indexOf方法

const arr = [1, 2, 3, 4, 1, 2, 3, 4]
const arr3 = arr.filter((item, index) => {
    return arr.indexOf(item) === index
})
console.log(arr3)

4.includes方法

const arr = [1, 2, 3, 4, 1, 2, 3, 4]
const arr4 = []
arr.forEach((item) => {
    if(!arr4.includes(item)) {
        arr4.push(item)
    }
})
console.log(arr4)

5.indexOf方法

const arr = [1, 2, 3, 4, 1, 2, 3, 4]
const arr5 = []
arr.forEach((item) => {
    if(arr5.indexOf(item) === -1) {
        arr5.push(item)
    }
})
console.log(arr5)

6.for循环

const arr = [1, 2, 3, 4, 1, 2, 3, 4]
const arr6 = []
for(let i = 0; i < arr.length; i++) {
    let bool = true
    for(let j = 0; j < arr6.length; j++) {
        if(arr[i] === arr6[j]) {
            bool = false
        }
    }
    if(bool) {
        arr6.push(arr[i])
    }
}
console.log(arr6)