使用字符串键访问嵌套的JavaScript对象

问题描述

我有这样的数据结构：

var someObject = {
    'part1' : {
        'name': 'Part 1',
        'size': '20',
        'qty' : '50'
    },
    'part2' : {
        'name': 'Part 2',
        'size': '15',
        'qty' : '60'
    },
    'part3' : [
        {
            'name': 'Part 3A',
            'size': '10',
            'qty' : '20'
        }, {
            'name': 'Part 3B',
            'size': '5',
            'qty' : '20'
        }, {
            'name': 'Part 3C',
            'size': '7.5',
            'qty' : '20'
        }
    ]
};

我想使用这些变量访问数据：

And I would like to access the data using these variable :

var part1name = "part1.name";
var part2quantity = "part2.qty";
var part3name1 = "part3[0].name";

part1name应填充 someObject.part1.name 的值，即第1部分。 part2quantity与60相同。

part1name should be filled with someObject.part1.name 's value, which is "Part 1". Same thing with part2quantity which filled with 60.

无论如何使用纯javascript或JQuery来实现这个目标吗？

Is there anyway to achieve this with either pure javascript or JQuery?

推荐答案

我刚刚根据我已经拥有的一些类似代码制作了它，它看似起作用：

I just made this based on some similar code I already had, it appears to work:

Object.byString = function(o, s) {
    s = s.replace(/\[(\w+)\]/g, '.$1'); // convert indexes to properties
    s = s.replace(/^\./, '');           // strip a leading dot
    var a = s.split('.');
    for (var i = 0, n = a.length; i < n; ++i) {
        var k = a[i];
        if (k in o) {
            o = o[k];
        } else {
            return;
        }
    }
    return o;
}

用法::

Object.byString(someObj, 'part3[0].name');

查看

编辑有些人注意到这段代码会抛出如果传递最左侧索引与对象中正确嵌套的条目不对应的字符串，则会出错。这是一个有效的问题，但恕我直言，在调用时最好用 try / catch 块解决，而不是让这个函数静默返回 undefined 表示无效索引。

EDIT some have noticed that this code will throw an error if passed a string where the left-most indexes don't correspond to a correctly nested entry within the object. This is a valid concern, but IMHO best addressed with a try / catch block when calling, rather than having this function silently return undefined for an invalid index.

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