如何在JavaScript中扁平化嵌套数组？[副本]

Question

如我们所知，要使用reduce()方法对数组[[0,1],[2,3],[4,5]]进行展平

var flattened = [[0, 1], [2, 3], [4, 5]].reduce(function(a, b) {
  return a.concat(b);
});

那么如何将这个数组[[[0],[1]],[[2],[3]],[[4],[5]]平坦化为[0,1,2,3,4,5]呢？

Answer 1

这是递归的一种替代方法（请参见这里的jsfiddle)，并且应该接受避免堆栈溢出的任何深度级别。

var array = [[0, 1], [2, 3], [4, 5, [6, 7, [8, [9, 10]]]]];
console.log(flatten(array), array); // does not mutate array
console.log(flatten(array, true), array); // array is now empty

// This is done in a linear time O(n) without recursion
// memory complexity is O(1) or O(n) if mutable param is set to false
function flatten(array, mutable) {
    var toString = Object.prototype.toString;
    var arrayTypeStr = '[object Array]';
    
    var result = [];
    var nodes = (mutable && array) || array.slice();
    var node;

    if (!array.length) {
        return result;
    }

    node = nodes.pop();
    
    do {
        if (toString.call(node) === arrayTypeStr) {
            nodes.push.apply(nodes, node);
        } else {
            result.push(node);
        }
    } while (nodes.length && (node = nodes.pop()) !== undefined);

    result.reverse(); // we reverse result to restore the original order
    return result;
}