A global library is one that can be accessed from the global scope (i.e. without using any form of import).\nMany libraries simply expose one or more global variables for use.\nFor example, if you were using jQuery, the $ variable can be used by simply referring to it:
\nts$(() => {\n console.log(\"hello!\");\n});
You’ll usually see guidance in the documentation of a global library of how to use the library in an HTML script tag:
\n\nhtml<script src=\"http://a.great.cdn.for/someLib.js\"></script>
Today, most popular globally-accessible libraries are actually written as UMD libraries (see below).\nUMD library documentation is hard to distinguish from global library documentation.\nBefore writing a global declaration file, make sure the library isn’t actually UMD.
\nGlobal library code is usually extremely simple.\nA global “Hello, world” library might look like this:
\n\njsfunction createGreeting(s) {\n return \"Hello, \" + s;\n}
or like this:
\n\njswindow.createGreeting = function (s) {\n return \"Hello, \" + s;\n};
When looking at the code of a global library, you’ll usually see:
\nvar statements or function declarationswindow.someNamedocument or window existYou won’t see:
\nrequire or definevar fs = require(\"fs\");define(...)require or import the libraryBecause it’s usually easy to turn a global library into a UMD library, very few popular libraries are still written in the global style.\nHowever, libraries that are small and require the DOM (or have no dependencies) may still be global.
\nYou can see an example DTS below:
\n","headings":[{"value":"Global Libraries","depth":2},{"value":"Identifying a Global Library from Code","depth":2},{"value":"Examples of Global Libraries","depth":2},{"value":"Global Library Template","depth":2}],"frontmatter":{"permalink":"/docs/handbook/declaration-files/templates/global-d-ts.html","title":"Global .d.ts","disable_toc":null,"oneline":null}},"prev":null,"next":null},"pageContext":{"id":"global-.d.ts","slug":"/docs/handbook/declaration-files/templates/global-d-ts.html","repoPath":"/packages/documentation/copy/en/declaration-files/templates/global.d.ts.md","lang":"en","modifiedTime":"2020-08-07T17:00:36.335Z"}}}ts// Type definitions for [~THE LIBRARY NAME~] [~OPTIONAL VERSION NUMBER~]\n// Project: [~THE PROJECT NAME~]\n// Definitions by: [~YOUR NAME~] <[~A URL FOR YOU~]>\n\n/*~ If this library is callable (e.g. can be invoked as myLib(3)),\n *~ include those call signatures here.\n *~ Otherwise, delete this section.\n */\ndeclare function myLib(a: string): string;\ndeclare function myLib(a: number): number;\n\n/*~ If you want the name of this library to be a valid type name,\n *~ you can do so here.\n *~\n *~ For example, this allows us to write 'var x: myLib';\n *~ Be sure this actually makes sense! If it doesn't, just\n *~ delete this declaration and add types inside the namespace below.\n */\ninterface myLib {\n name: string;\n length: number;\n extras?: string[];\n}\n\n/*~ If your library has properties exposed on a global variable,\n *~ place them here.\n *~ You should also place types (interfaces and type alias) here.\n */\ndeclare namespace myLib {\n //~ We can write 'myLib.timeout = 50;'\n let timeout: number;\n\n //~ We can access 'myLib.version', but not change it\n const version: string;\n\n //~ There's some class we can create via 'let c = new myLib.Cat(42)'\n //~ Or reference e.g. 'function f(c: myLib.Cat) { ... }\n class Cat {\n constructor(n: number);\n\n //~ We can read 'c.age' from a 'Cat' instance\n readonly age: number;\n\n //~ We can invoke 'c.purr()' from a 'Cat' instance\n purr(): void;\n }\n\n //~ We can declare a variable as\n //~ 'var s: myLib.CatSettings = { weight: 5, name: \"Maru\" };'\n interface CatSettings {\n weight: number;\n name: string;\n tailLength?: number;\n }\n\n //~ We can write 'const v: myLib.VetID = 42;'\n //~ or 'const v: myLib.VetID = \"bob\";'\n type VetID = string | number;\n\n //~ We can invoke 'myLib.checkCat(c)' or 'myLib.checkCat(c, v);'\n function checkCat(c: Cat, s?: VetID);\n}