数组去重的 6 种方法

Posted 2021-09-27 乱舞春秋__

数组去重常见方法

1. 利用Set

    const arr = [1, 2, 1, '3', '3', true, true, {}, {}]
    Array.from(new Set(arr)) //[1, 2, '3', true, {}, {}]

2. 利用splice( )方法

    const arr = [1, 2, 1, '3', '3', true, true, {}, {}]
    const removeDuplicates = arr => {
      let n = arr.length
      for (let i = 0; i < n; ++i) {
        for (let j = i + 1; j < n; ++j) {
          if (arr[i] === arr[j]) {
            arr.splice(j, 1)
            --n
            --j
          }
        }
      }
      return arr
    }
    removeDuplicates(arr) //[1, 2, '3', true, {}, {}]

3. 利用indexOf( )方法

    const arr = [1, 2, 1, '3', '3', true, true, {}, {}]
    const removeDuplicates = arr => {
      const ans = []
      for (let i = 0; i < arr.length; ++i) {
        if (ans.indexOf(arr[i]) === -1) ans.push(arr[i])
      }
      return ans
    }
    removeDuplicates(arr) //[1, 2, '3', true, {}, {}]

4. 利用includes( )方法

    const arr = [1, 2, 1, '3', '3', true, true, {}, {}]
    const removeDuplicates = arr => {
      const ans = []
      for (let i = 0; i < arr.length; ++i) {
        if (!ans.includes(arr[i])) ans.push(arr[i])
      }
      return ans
    }
    removeDuplicates(arr) //[1, 2, '3', true, {}, {}]

5. 利用filter方法

    const arr = [1, 2, 1, '3', '3', true, true, {}, {}]
    const removeDuplicates = arr => {
      return arr.filter((v, i) => {
        return arr.indexOf(v) === i
      })
    }
    removeDuplicates(arr) //[1, 2, '3', true, {}, {}]

6. 利用Map

    const arr = [1, 2, 1, '3', '3', true, true, {}, {}]
    const removeDuplicates = arr => {
      const map = new Map()
      const ans = []
      for (let i = 0; i < arr.length; ++i) {
        if (!map.has(arr[i])) {
          map.set(arr[i], arr[i])
          ans.push(arr[i])
        }
      }
      return ans
    }
    removeDuplicates(arr) //[1, 2, '3', true, {}, {}]

以上即为常见的数组去重方法。