ECMAScript-数组去重

提示：方法不唯一

方法一：双层for循环

function arrayRepeat (arr) {
  for (var i = 0; i < arr.length; i++) {
    for (var j = i + 1; j < arr.length; j++) {
      if (arr[i] == arr[j]) {
        arr.splice(j, 1)
        j--
      }
    }
  }
  console.log(arr)
}

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方法二：indexOf

function arrayRepeat (arr) {
  let newArr = []
  arr.forEach(item => {
    if (newArr.indexOf(item) < 0) {
      newArr.push(item)
    }
  });
  console.log(newArr)
}

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includes：

function arrayRepeat (arr) {
  let newArr = []
  arr.forEach((item) => {
    if (!newArr.includes(item)) {
      newArr.push(item)
    }
  })
  console.log(newArr)
}

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filter+indexOf/filter+includes：

function arrayRepeat (arr) {
  let newArr = []
  arr.filter(item => {
    return !newArr.includes(item) ? newArr.push(item) : ""
  //return newArr.indexOf(item)<0 ? newArr.push(item) : ""
  })
  console.log(newArr)
}

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set：

function arrayRepeat (arr) {
  let newArr = []
  let set = new Set(arr)
  // newArr = Array.from(set)
  newArr = [...set]
  console.log(newArr)
}

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