用于平展多维数组的函数[重复]

Question

var flatten = function (array){
  // TODO: Program me
  var newArray = [];
  for(var i = 0; i<array.length; i++) {
    newArray.push(array[i]);
  }
  return newArray;
}

以下是例外的结果：

flatten([1,2,3]) // => [1,2,3]
flatten([[1,2,3],["a","b","c"],[1,2,3]])  // => [1,2,3,"a","b","c",1,2,3]
flatten([[[1,2,3]]]) // => [[1,2,3]]

Test result:

Test Passed

Test Passed

Test Failed: Value is not what was expected

null

Answer 1

诀窍在于，如果输入数组的一个元素本身就是一个数组，那么您应该将该元素的扁平项“连接”到输入数组中，而不是将整个数组推入。

下面是一个使用“reduce”和“array.isArray（...）”的解决方案。仅在支持ECMAScript 5.1Th Edition更高规格的较新浏览器中提供：

javascript prettyprint-override">function flatten(array) {
  return array.reduce(function(memo, el) {
    var items = Array.isArray(el) ? flatten(el) : [el];
    return memo.concat(items);
  }, []);
}

flatten([1,2,3])                          // => [1,2,3]
flatten([[1,2,3],["a","b","c"],[1,2,3]])  // => [1,2,3,"a","b","c",1,2,3]
flatten([[[1,2,3]]])                      // => [1, 2, 3]