typescript - 实现可索引接口(interface)

Question

我将如何实现可索引的接口(interface):

interface fooInterface{
    // indexable
    [index:string]:number;
    [index:number]:number;          
}


class Foo implements fooInterface{
    // What goes here? 
}

Answer 1

你永远不会在类定义中实现它，而只能通过寻址 instance[index]，所以你的 fooInterface 不能通过 implements 使用 在 TypeScript 类上，但可用于描述对象的预期结构，例如var foo: fooInterface = {};

Describing an Indexable Object

A common pattern in JavaScript is to use an object (e.g. {}) as way to map from a set of strings to a set of values. When those values are of the same type, you can use an interface to describe that indexing into an object always produces values of a certain type (in this case, Widget).

interface WidgetMap {
    [name: string]: Widget;
}

var map: WidgetMap = {};
map['gear'] = new GearWidget();
var w = map['gear']; // w is inferred to type Widget

引用和小部件示例取自:http://blogs.msdn.com/b/typescript/archive/2013/01/24/interfaces-walkthrough.aspx