通过Javascript中的keyPath访问属性? [英] Access property via it's keyPath in Javascript?

问题描述

我有

data = 
{
    'first': {
        'number': 1,
        'text': 'Ya.'
    },
    'second': {
        'number': 10,
        'text': 'Da.'
    }
};

我真的想像这样访问它:

And I really want to access it like:

number = data['first.number'];

实际上以更灵活的方式，例如:

Actually in a more flexible way, like:

numberOrText = data[memberName+'.'+propertyName];

---

您有没有建议的轻量级库或摘要? 这是- https://github.com/martinvl/KVCObject -很酷，但是有点开销这个.

---

Is there any lightweight library, or snippet you can suggest? This is - https://github.com/martinvl/KVCObject - so cool, but a bit overhead for this.

推荐答案

基于 @dandavis

Based on @dandavis pretty simple suggestions, I can set up accessors as prototype properties.

否eval ，在使用Object.defineProperty 进行枚举方面，Object.prototype也保持不变.

解决方案实际上是这样的:

The solution actually goes like this:

function stringContains(string, value)
{ return string.indexOf(value) != -1; }

Object.defineProperty(Object.prototype, "setValueForKey", { value: function(value, key)
{ this[key] = value; }});

Object.defineProperty(Object.prototype, "setValueForKeyPath", { value: function(value, keyPath)
{
    if (keyPath == null) return;
    if (stringContains(keyPath, '.') == false) { this.setValueForKey(value, keyPath); return; }

    var chain = keyPath.split('.');
    var firstKey = chain.shift();
    var shiftedKeyPath = chain.join('.');

    this[firstKey].setValueForKeyPath(value, shiftedKeyPath);
}});

Object.defineProperty(Object.prototype, "getValueForKey", { value: function(key)
{ return this[key]; }});

Object.defineProperty(Object.prototype, "getValueForKeyPath", { value: function(keyPath)
{
    if (keyPath == null) return;
    if (stringContains(keyPath, '.') == false) { return this.getValueForKey(keyPath); }

    var chain = keyPath.split('.');
    var firstKey = chain.shift();
    var shiftedKeyPath = chain.join('.');

    return this[firstKey].getValueForKeyPath(shiftedKeyPath);
}});

测试很好:

data = {
    'name' : 'data',
    'first': {
        'number': 1,
        'text': 'Ya.',
        'meta' : {
            'lang' : 'en'
        }
    },
    'second': {
        'number': 10,
        'text': 'Ba.',
        'meta' : {
            'lang' : 'en'
        }
    },
    'third': {
        'number': 100,
        'text': 'Da.',
        'meta' : {
            'lang' : 'hu'
        }
    }
};

data.setValueForKey('chunk', 'name');
data.setValueForKeyPath('blob', 'name');

var thirdLanguage = data.getValueForKeyPath('third.meta.lang');
data.setValueForKeyPath(thirdLanguage, 'first.meta.lang');
data.setValueForKeyPath(thirdLanguage, 'second.meta.lang');

log(data);

hu的输出与每个数据成员中的语言相同.

Output is the same with hu as language in every data member.

这篇关于通过Javascript中的keyPath访问属性?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！