Javascript:如何从点分隔的字符串创建对象? [英] Javascript: How to create an object from a dot separated string?

问题描述

我遇到了这个潜在的场景，我向我的一些员工提出了一个测试问题.我可以想到几种方法来解决这个问题，但它们都不是很漂亮.我想知道什么解决方案可能最适合这个以及任何优化技巧.问题来了:

I ran into this potential scenario that I posed to a few of my employees as a test question. I can think of a couple ways to solve this problem, but neither of them are very pretty. I was wondering what solutions might be best for this as well as any optimization tips. Here's the question:

给定一些任意长度的点符号中的任意字符串mystr"(例如mystr =node1.node2.node3.node4")，编写一个名为expand"的函数，它将创建这些项目中的每一个作为一个新的节点层在 js 对象中.对于上面的示例，它应该输出以下内容，因为我的对象名称是blah":

Given some arbitrary string "mystr" in dot notation (e.g. mystr = "node1.node2.node3.node4") at any length, write a function called "expand" that will create each of these items as a new node layer in a js object. For the example above, it should output the following, given that my object name is "blah":

blah: { node1: { node2: { node3: { node4: {}}}}}

来自函数调用:

mystr = "node1.node2.node3.node4";
blah = {};
expand(blah,mystr);

或者，如果更简单，可以创建函数来将变量设置为返回值:

Alternately, if easier, the function could be created to set a variable as a returned value:

mystr = "node1.node2.node3.node4";
blah = expand(mystr);

额外的功劳:有一个可选的函数参数，用于设置最后一个节点的值.所以，如果我调用我的函数expand"并像这样调用它:expand(blah, mystr, "value")，输出应该和以前一样，但是用 node4 = "value" 而不是 {}.

Extra credit: have an optional function parameter that will set the value of the last node. So, if I called my function "expand" and called it like so: expand(blah, mystr, "value"), the output should give the same as before but with node4 = "value" instead of {}.

推荐答案

这是我脑海中突然出现的一个方法.它使用点符号分割字符串，然后循环遍历节点以在对象内部创建对象，使用移位引用"(但不确定这是否是正确的术语).

Here's a method that popped up in my mind. It splits the string on the dot notation, and then loops through the nodes to create objects inside of objects, using a 'shifting reference' (not sure if that's the right term though).

函数内的对象 output 包含在整个函数中构建的完整对象，但 ref 在 output<中保留了一个越来越深的引用/code>，因为在 for 循环中创建了新的子对象.

The object output within the function contains the full object being built throughout the function, but ref keeps a reference that shifts to deeper and deeper within output, as new sub-objects are created in the for-loop.

最后，最后一个值应用于最后一个给定的名称.

Finally, the last value is applied to the last given name.

function expand(str, value)
{
    var items = mystr.split(".") // split on dot notation
    var output = {} // prepare an empty object, to fill later
    var ref = output // keep a reference of the new object

    //  loop through all nodes, except the last one
    for(var i = 0; i < items.length - 1; i ++)
    {
        ref[items[i]] = {} // create a new element inside the reference
        ref = ref[items[i]] // shift the reference to the newly created object
    }

    ref[items[items.length - 1]] = value // apply the final value

    return output // return the full object
}

然后返回对象，因此可以使用此表示法:

The object is then returned, so this notation can be used:

mystr = "node1.node2.node3.node4";
blah = expand(mystr, "lastvalue");

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