展开JS对象并转换数组 [英] Unflatten JS object and convert arrays

问题描述

我有一个用于平整对象的函数，如下所示:

I have a function used to flatten objects like so:

let object = {
  a: 1,
  b: [
   { c: 2 },
   { c: 3 }
  ]
};

flatten(object)
// returns {
  'a': 1,
  'b.0.c': 2,
  'b.1.c': 3
}

我需要展开对象，还要将数组还原为原来的样子.我有以下代码:

I need to unflatten objects, but also revert arrays to how they were. I have the following code:

  unflatten(obj) {
    let final = {};

    for (let prop in obj) {
      this.assign(final, prop.split('.'), obj[prop]);
    }

    return final;
  }

  assign(final, path, value) {
     let lastKeyIndex = path.length-1;
     for (var i = 0; i < lastKeyIndex; ++ i) {
       let key = path[i];
       if (!(key in final)) {
         final[key] = {};
       }
       final = final[key];
     }
     final[path[lastKeyIndex]] = value;
  }

在大多数情况下都有效，但是它像这样对待数组:

which works for the most part, but it treats arrays like so:

{
  a: 1,
  b: { // Notice how b's value is now an object
   "0": { c: 2 }, // Notice how these now have a key corresponding to their index
   "1": { c: 3 }
  }
}

我需要b像以前一样是一个数组:

Whereas I need b to be an array like before:

{
  a: 1,
  b: [
   { c: 2 },
   { c: 3 }
  ]
}

我不知道该从哪里去.它需要能够处理任意数量的数组，例如:

I'm at a loss for where to go from here. It needs to be able to deal with an arbitrary number of arrays like:

'a.b.0.c.0.d',
'a.b.0.c.1.d',
'a.b.1.c.0.d',
'a.b.1.c.1.d',
'a.b.1.c.2.d',
// etc

它必须是原始JS，但es2015很好.它假定任何一个数字键实际上都是数组的一部分.

It needs to be vanilla JS, but es2015 is fine. It it assumed that any key that's a number is actually part of an array.

如果有人有任何建议，我们将不胜感激！

If anyone has any advice, it's appreciated!

推荐答案

当发现key不在final中时，应检查路径中的下一个键是否仅为数字(使用常规表达式)，如果是这样，则分配给数组而不是对象:

When you find that key is not in final, you should check to see if the next key in the path is only digits (using a regular expression) and, if so, assign to an array instead of an object:

if (!(key in final)) {
  final[key] = /^\d+$/.test(path[i + 1]) ? [] : {};
}

let object = {
  a: 1,
  b: [{
      c: 2
    },
    {
      c: 3
    }
  ]
};

let flattened = {
  'a': 1,
  'b.0.c': 2,
  'b.1.c': 3
}

function unflatten(obj) {
  let final = {};

  for (let prop in obj) {
    assign(final, prop.split('.'), obj[prop]);
  }

  return final;
}

function assign (final, path, value) {
  let lastKeyIndex = path.length - 1;
  for (var i = 0; i < lastKeyIndex; ++i) {
    let key = path[i];
    if (!(key in final)) {
      final[key] = /^\d+$/.test(path[i + 1]) ? [] : {};
    }
    final = final[key];
  }
  final[path[lastKeyIndex]] = value;
}

console.log(unflatten(flattened))

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