对于修改了全局作用域的模块来讲,在导入它们时,会对全局作用域中的值进行修改。
比如存在某个代码库,当导入它时,它会向String.prototype
上添加新的成员。
该模式存在危险,因为它有导致运行时冲突的可能性,
但我们仍然可以为其编写声明文件。
我们可以通过文档来识别修改了全局作用域的模块。
通常来讲,它们与全局插件类似,但是需要require
语句来激活。
你可能看到过如下的文档:
// 'require' call that doesn't use its return value
var unused = require('magic-string-time');
/* or */
require('magic-string-time');
var x = 'hello, world';
// Creates new methods on built-in types
console.log(x.startsWithHello());
var y = [1, 2, 3];
// Creates new methods on built-in types
console.log(y.reverseAndSort());
以下是一个示例:
// Type definitions for [~THE LIBRARY NAME~] [~OPTIONAL VERSION NUMBER~]
// Project: [~THE PROJECT NAME~]
// Definitions by: [~YOUR NAME~] <[~A URL FOR YOU~]>
/*~ This is the global-modifying module template file. You should rename it to index.d.ts
*~ and place it in a folder with the same name as the module.
*~ For example, if you were writing a file for "super-greeter", this
*~ file should be 'super-greeter/index.d.ts'
*/
/*~ Note: If your global-modifying module is callable or constructable, you'll
*~ need to combine the patterns here with those in the module-class or module-function
*~ template files
*/
declare global {
/*~ Here, declare things that go in the global namespace, or augment
*~ existing declarations in the global namespace
*/
interface String {
fancyFormat(opts: StringFormatOptions): string;
}
}
/*~ If your module exports types or values, write them as usual */
export interface StringFormatOptions {
fancinessLevel: number;
}
/*~ For example, declaring a method on the module (in addition to its global side effects) */
export function doSomething(): void;
/*~ If your module exports nothing, you'll need this line. Otherwise, delete it */
export {};