如何在私有对象上设置特定属性 [英] How to set a specific property on a private object

问题描述

我希望能够通过为值提供 not 表示法路径来在 private 对象上设置属性.困难在于这个对象在闭包内，所以我不能直接访问它来以正常方式设置值(例如 dot.notation.path = 'new value').这看起来很奇怪，但我想不出明显的方法.

I want to be able to set a property on a private object by giving the not notation path to the value. The difficulty is that this object is within closure so I can't access it directly to set the value the normal way (eg. dot.notation.path = 'new value'). This seems weird but I can't think of the obvious way.

示例:

// setter function   
function set(path, change){
    var privateObject = {
      a: 'a',
      b: 'b',
      c: {
          d: 'd',
          e: 'e'
      }
    }

    privateObject[path] = change;
    return privateObject;
}

// execution
var result = set('c.d', 'new value'); 

// desired result
//{
//  a: "a"
//  b: "b"
//  c: {
//    d: "new value",
//    e: 'e'
//  }
//}

// actual result
//{
//  a: "a"
//  b: "b"
//  c: {
//    d: 'd',
//    e: 'e'
//  }
//  c.d: "new value"
//}

工作示例:

失败的 JSFiddle 示例 >>

[更新] 替代示例:

工作 JSFiddle 示例 >>

推荐答案

你真的很接近，但括号表示法不会为你处理点(它不能 —点是完全有效的属性字符名称).你必须自己做:

You're really close, but the bracket notation won't handle dots for you (it can't — the dots are perfectly valid characters for property names). You have to do that yourself:

function set(path, change){
  var privateObject = {
        a: 'a',
        b: 'b',
        c: {
            d: 'd',
            e: 'e'
        }
      },
      index,
      parts,
      obj;

  parts = path.split(".");
  obj = privateObject;
  if (parts.length) {
    index = 0;
    while (index < parts.length - 1) {
      obj = obj[parts[index++]];
    }
    obj[parts[index]] = change;
  }
  return privateObject;
}

现场演示

我认为它在旧引擎上并不是非常高效，我也没有费心去探索故障模式，但是你明白了:分割你在点上给出的路径，然后使用每个组成部分页面.

I dashed that off, it's not hyper-efficient on older engines and I didn't bother to explore failure modes, but you get the idea: Split the path you're giving on the dot, then use each component part of the page.

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