如何在 Typescript 中定义数字-> 字符串字典？
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how do I define a number->string dictionary in Typescript?
提问by KallDrexx
I'm playing with Typescript and converting over a small library over to it from Javascript. In one area of the code there was a statically defined mapping of friendly key name to their keycode. The original code looked like:
我正在使用 Typescript 并将一个小型库从 Javascript 转换为它。在代码的一个区域中，有一个静态定义的友好密钥名称到它们的密钥代码的映射。原始代码如下所示：
keys: { "Backspace": 8, "Tab": 9, "Enter": 13, ....etc.. };
I defined this in typescript via:
我通过以下方式在打字稿中定义了这一点：
static keys: { [name: string]: number; } = { "Backspace": 8, "Tab": 9, "Enter": 13, ... etc.. };
This seems to work fine, however another part of the code uses the opposite mapping:
这似乎工作正常，但是代码的另一部分使用相反的映射：
chars: {8:"Backspace",9:"Tab",13:"Enter", ...etc... };
So I tried to do the same type of definition in typescript that I did previously:
因此，我尝试在打字稿中进行与我之前所做的相同类型的定义：
chars: { [code: number]: string; } = { 8: "Backspace", 9: "Tab", 13: "Enter", ...etc.. };
This fails to compile with the following error:
这无法编译并出现以下错误：
Cannot convert '{ 0: string; 1: string; 2: string; 4: string; 8: string; 9: string; : string; }' to '{ [name: number]: string; }': Index signatures of types '{ 0: string; 1: string; 2: string; 4: string; 8: string; 9: string; : string; }' and '{ [name: number]: string; }' are incompatible
无法转换 '{ 0: string; 1：字符串；2：字符串；4：字符串；8：字符串；9：字符串；： 细绳; }' 到 '{ [名称：编号]：字符串；}': '{ 0: string; 类型的索引签名 1：字符串；2：字符串；4：字符串；8：字符串；9：字符串；： 细绳; }' 和 '{ [名称：编号]：字符串；}' 不兼容
How do I define this mapping in Typescript?
我如何在 Typescript 中定义这个映射？
回答by MiMo
The problem is that in JavaScript - and hence in TypeScript - the keys of an object literal are always strings, and so it cannot be assigned to a variable with a number indexer.
问题在于，在 JavaScript 中——因此在 TypeScript 中——对象字面量的键始终是字符串，因此不能将其分配给带有数字索引器的变量。
An object with a number indexer is an array - and so you have to do this:
带有数字索引器的对象是一个数组 - 所以你必须这样做：
var chars: string[] = [];
chars[8]= "Backspace";
chars[9]= "Tab";
chars[13] = "Enter";
回答by Doug
Here's a library called Classical.js* that may help you accomplish this and similar problems. It defines, among other things, a doubly generic dictionary. For your use case, the code would look like this:
这是一个名为 Classical.js*的库，可以帮助您解决此问题和类似问题。除其他外，它定义了双重通用字典。对于您的用例，代码如下所示：
import c = Classical.Collections;
var keys = new c.Dictionary<string, number>();
keys.add("Backspace", 8);
keys.add("Tab", 9);
keys.add("Enter", 13);
//etc...
keys.getValue("Backspace"); //8
keys.getValue("Tab"); //9
keys.getValue("Enter"); //13
//etc...
Dictionary<TKey, TValue> works with all types of objects and doesn't have issues with name collisions such as keys named 'constructor'.
Dictionary<TKey, TValue> 适用于所有类型的对象，并且不会出现名称冲突问题，例如名为“构造函数”的键。
For the opposite mapping you could either construct the inverse dictionary or query the current one like so:
对于相反的映射，您可以构建逆字典或查询当前字典，如下所示：
keys.query().single(pair => pair.key === 8).value; //"Backspace"
keys.query().single(pair => pair.key === 9).value; //"Tab"
keys.query().single(pair => pair.key === 13).value; //"Enter"
//etc...
If you'd like to give it a try, visit Classical, open up the bin folder and add classical.js and classical.d.ts to your project.
如果您想尝试一下，请访问Classical，打开 bin 文件夹并将 classic.js 和 classic.d.ts 添加到您的项目中。
Hope that helps.
希望有帮助。
* I am one of the developers on the classical team
* 我是经典团队的开发者之一
回答by basarat
Indeed js internally only has string based indices (with Array being different from {}) but string / number conversion is stable in js :
实际上，js 内部只有基于字符串的索引（Array 与 {} 不同），但字符串/数字转换在 js 中是稳定的：
var x = {0 : "asdf",1:"bb"}
alert(x[0])
alert(x[1])
I think typescript should support it as well and created a work item you can vote on: http://typescript.codeplex.com/workitem/832
我认为打字稿也应该支持它并创建了一个您可以投票的工作项目：http: //typescript.codeplex.com/workitem/832
