如何在TypeScript中定义全局函数?

您正在为编译器定义类型,但实际上并没有将其附加到全局命名空间 window 在浏览器中, global 在节点中。与其从模块中导出,不如附加它。对于同构使用,请使用类似于。。。

function s() { ... }

// must cast as any to set property on window
const _global = (window /* browser */ || global /* node */) as any
_global.s = s

你也可以抛弃 .d.ts 文件并在同一文件中声明类型,使用 declare global ,例如。

// we must force tsc to interpret this file as a module, resolves
// "Augmentations for the global scope can only be directly nested in external modules or ambient module declarations."
// error
export {}

declare global {
  function s<T>(someObject: T | null | undefined, defaultValue?: T | null | undefined) : T;
}

const _global = (window /* browser */ || global /* node */) as any
_global.s = function<T>(object: T | null | undefined, defaultValue: T | null = null) : T {
  if (typeof object === 'undefined' || object === null)
    return defaultValue as T;
  else
    return object;
}

感谢@Romain Deneau。他的回答对我有用。 这是我的简化版,让它看起来更容易理解他的答案。 (我的假设脚本在浏览器上运行。此外,我省略了函数的签名 s .)

在任何类之外定义函数。

function s() {
    console.log("invoked s()!");
}

(window as any).s = s;

使用此全局函数 s 从TypeScript类如下;

declare var s;

export class MyClass {
    public static callFunctionS() {
        s();
    }
}

global.ts(x) 只需稍加调整即可成为有效的“全局模块” (仅具有副作用的模块) :删除 export 关键字并添加一些代码来扩充全局对象。您还可以在同一个文件中提供全局声明并删除 global.d.ts .

function _s<T>(object: T | null, defaultValue: T = {} as T) : T {
    return object == null
        ? defaultValue
        : object as T;
}

// Global declaration
declare var s: typeof _s;

// Global scope augmentation
var window = window || null;
const _global = (window || global) as any;
_global.s = _s;

要使用它,只需导入模块一次,例如 App.tsx 通过全球进口: import './global'; .

使用mocha、chai、ts节点测试:

import { expect } from 'chai';
import './global'; // To do once at app bootstrapping

describe('global s()', () => {
    it('should replace null with empty object', () => {
        const result = s(null);
        expect(result).to.eql({});
    });

    it('should replace undefined with empty object', () => {
        const result = s(undefined);
        expect(result).to.eql({});
    });

    it('should replace null with the given default value', () => {
        const defVal = { def: 'val' };
        const result = s(null, defVal);
        expect(result).to.eql({ def: 'val' });
    });

    it('should preserve defined object', () => {
        const object = { bar: 'a' };
        const result = s(object);
        expect(result).to.eql(object);
    });
});