如何在JavaScript中创建双向映射，或通过其他方式交换值? [英] How can I create a two-way mapping in JavaScript, or some other way to swap out values?

问题描述

我目前需要临时交换JavaScript字符串中的值，因此，我将需要一个双向的map/hash对象.

I currently have a need to temporarily swap out values in a JavaScript string, and therefore I will need to have a two-way map/hash thing.

例如，假设我想将\*更改为__asterisk__(这只是一个示例，这不是我实际上要执行的操作).我必须能够将*映射到__asterisk__(以交换原始字符串中的值)，但是然后我还必须能够将__asterisk__映射回*(以返回原始字符串).

For example, let's say I want to change \* to __asterisk__ (this is just an example, it's not what I'm actually trying to do). I'll have to be able to map * to __asterisk__ (to swap out the value in the original string), but then I'll also have to be able to map __asterisk__ back to * (to get the original string back).

这里有一些我想要的快速伪伪代码，因此您可以更好地理解它:

Here's some quick pseudo-ish code of the kind of thing that I'm looking for, so you can understand it better:

var myString = 'this is \* a test';

// ???
var twoWayMap = new TwoWayMap('*' <---> '__asterisk__', '%' <---> '__percent__', ...);

var newString = myString.replace(/\\(.)/g, function(m, c) {
    return twoWayMap.getKey(c);
});
// newString is now 'this is __asterisk__ a test'

// ... later in the code ...

var oldString = newString.replace(/__([^_]+)__/g, function(m, c) {
    return twoWayMap.getValue(c);
});
// oldString is now 'this is * a test'

这是我到目前为止一直在考虑和尝试的事情:

This is what I've thought about and tried so far:

var twoWayMap = {'*': '__asterisk__', '%': '__percent__', ...};

// getKey would be like this:
twoWayMap[c];
// getValue would be like:
var val; for (var x in twoWayMap) { if (twoWayMap[x] === c) { val = x; break } }

一个明显的问题是，获取价值的方法太复杂了，我不想每次都要反向查找时都必须写出全部内容.

The obvious problem with this is that the way to get by value is much too complicated, and I don't want to have to write out the whole thing every single time I have to reverse lookup.

我只是想知道:有什么方法可以解决这个问题而无需求助于遍历一个对象?如果没有，有什么方法可以使它更容易或更清洁?

I just wanted to know: Is there any way to solve this problem without resorting to looping through an object? If not, is there any way to make it easier or cleaner?

推荐答案

使用两个对象.一个对象包含* -> _asterisk_映射，另一个对象包含_asterisk_ -> *.

Use two objects. One object contains the * -> _asterisk_ mapping, the other object contains _asterisk_ -> *.

var forwardMap = {'*': '__asterisk__', '%': '__percent__', ...};
var reverseMap = {};
for (var key in forwardMap) {
    if (forwardMap.hasOwnProperty(key)) {
        reverseMap[forwardMap[key]] = key;
    }
}

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