「JavaScript」数组扁平化

example

var arr = [[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10];
console.log(flatten(arr));  // [1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12, 13, 14, 10]

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1. 不使用数组api递归+拓展运算符

function flatten(arr) => {
  let resArr = [];
  for (let i = 0; i < arr.length; i++) {
    if (typeof arr[i] == "object") {
      resArr = [...resArr, ...flatten(arr[i])];
    } else {
      resArr[resArr.length] = arr[i];
    }
  }
  return resArr;
}

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2. toString+split

function flatten(arr) {
  return arr.toString().split(',').map(Number)
}

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3. reduce+concat+递归

function flatten(arr) {
  return arr.reduce((res, cur) => {
    return res.concat(Array.isArray(cur) ? flatten(cur) : cur);
  }, []);
}

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4. some+concat

function flatten(arr) {
  while (arr.some((item) => Array.isArray(item))) {
    arr = [].concat(...arr);
  }
  return arr;
}

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5. 正则+json

function flatten(arr) {
  let str = JSON.stringify(arr);
  str = str.replace(/(\[|\])/g, "");
  str = "[" + str + "]";
  return JSON.parse(str);
}

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6. flat

console.log(arr.flat(Infinity)) // 参数为深度

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