在循环中创建一个深度（水平）对象

Question

我不确定表达这个问题的最佳方式是什么，但基本上我希望创建一个循环来创建如下对象：

var dictionary = {};
var arr = [
              ["for", "item", "in", "list"],
              ["if", "condition"]
          ];

// Insert Magic Loop to yield:

dictionary.for.item.in.list // {} (exists, as well as rest of chain)
dictionary.if.condition     // {} (exists, as well as rest of chain)
dictionary.for.item         // {}
dictionary.test             // undefined

Answer 1

我的脑海中浮现出：

function create(arrArray) {
   for(var i = 0; i < arrArray.length; i++) {
       var arr = arrArray[i];

       var _dict = dictionary;

       for(var j = 0; j < arr.length; j++) {
           if(!_dict[arr[j]]) {
              _dict[arr[j]] = {};
           }
           _dict = _dict[arr[j]];
       } 
   }
}

编辑

这是解决方案的一个子集。我写了一个函数，它接受一个数组和一个字典作为参数：

function create(arr, dict) {           
    var _dict = dict;

    for(var j = 0; j < arr.length; j++) {
        if(!_dict[arr[j]]) {
           _dict[arr[j]] = {};
        }
        _dict = _dict[arr[j]];
    } 
}

var dictionary = {};

create(["for", "item", "in", "list"], dictionary);
create(["if", "condition"], dictionary)

如果你不担心覆盖，你可以去掉循环中的 if ：

function create(arr, dict) {           
    var _dict = dict;

    for(var j = 0; j < arr.length; j++) {
        _dict[arr[j]] = {};
        _dict = _dict[arr[j]];
    } 
}

并且为了更好的可读性：

function create(arr, dict) {           
    var _dict = dict;

    for(var j = 0; j < arr.length; j++) {
        var key = arr[j];
        _dict[key] = {};
        _dict = _dict[key];
    } 
}

Answer 2

var dictionary = {};
var arr = [
              ["for", "item", "in", "list"],
              ["if", "condition"]
          ];
for(var i in arr){
    var _i = arr[i];
    var x = dictionary;
    for(var ii in _i){
        x[_i[ii]] = {};
        x = x[_i[ii]];
    }
}
console.log(dictionary);
console.log(dictionary.for.item.in.list);
console.log(dictionary.if.condition );
console.log(dictionary.for.item);
console.log(dictionary.test );

Answer 3

这将需要一些修改（每个序列从顶部重新启动），但显示了降序向下的总体思路：

var arr = ["foo", "if", "then", "bar"]
var dictionary = {}
var obj = dictionary // keep original
for (var i = 0; i < arr.length; i++) {
   var key = arr[i]
   // assign and "move to next".
   // this could be done as `obj = obj[key] = {}`
   obj[key] = {}
   obj = obj[key]
}

快乐编码

Answer 4

var dictionary = {},
    arr = [
          ["for", "item", "in", "list"],
          ["if", "condition"]
    ];

// loop the outer array
for (var x = 0; x < arr.length; x++) {
    var current = dictionary, // set "current" to the top-level object (dictionary)
        sub = arr[x];     // reference to sub-item

    // loop sub-list
    for (var y = 0; y < sub.length; y++) {
        // create the new object on the "current" object,
        // then assign that new object to be "current"
        current = current[sub[y]] = {};
    }
}

console.log(dictionary);