Angular 2官方教程-打字文件夹

Question

The readme file in https://github.com/angular/quickstart/blob/master/README.md suggests that:

If the typings folder doesn't show up after npm install please install them manually with: npm run typings -- install

Running this command also helped me with a different repo I cloned. Can someone explain what this means? I read about typings lib, but don't understand why it requires a separate step?

Answer 1

typing is a library to install TypeScript definition of external libraries that are not coded using TypeScript. Using typing, you can install TypeScript definition of JavaScript libraries and get the autocomplete\\validation of classes in TypeScript.

typings install do the download and installation of all the Typescript definition required and stored into the typings.json.

On the contrary, npm install usually installs only the npm dependencies. Usually they are two separated stages.

EDIT: To address your question, at the end: in the post install of the package.json there is this configuration: "postinstall": "typings install". Maybe, for some reason, it does not always work. So if does not create the typings folder after npm install they say to run the command manually.