1、如果是可调用的方法，需要像下面这样声明：

declare function myLib(a: string): string;declare function myLib(a: number): number;

调用的时候像这样: 

myLib(3)

2、如果希望此库的名称是有效的类型名称：

interface myLib {    name: string;    length: number;    extras?: string[];}

你调用的时候会这样：

var x: myLib

3、如果您的库具有在全局变量上公开的属性：

declare namespace myLib {    //~ We can write 'myLib.timeout = 50;'    let timeout: number;    //~ We can access 'myLib.version', but not change it    const version: string;    //~ There's some class we can create via 'let c = new myLib.Cat(42)'    //~ Or reference e.g. 'function f(c: myLib.Cat) { ... }    class Cat {        constructor(n: number);        //~ We can read 'c.age' from a 'Cat' instance        readonly age: number;        //~ We can invoke 'c.purr()' from a 'Cat' instance        purr(): void;    }    //~ We can declare a variable as    //~   'var s: myLib.CatSettings = { weight: 5, name: "Maru" };'    interface CatSettings {        weight: number;        name: string;        tailLength?: number;    }    //~ We can write 'const v: myLib.VetID = 42;'    //~  or 'const v: myLib.VetID = "bob";'    type VetID = string | number;    //~ We can invoke 'myLib.checkCat(c)' or 'myLib.checkCat(c, v);'    function checkCat(c: Cat, s?: VetID);}