How to get the information about an npm package

中文 Chinese Version

We can certainly look up information about a package by visiting the npm official website (opens in a new tab), but this approach has some drawbacks.

• You need to open a tab in the browser to look up the package
• You need to click on the "Dependency" navigation bar to view the Dependency
• Dependency only shows package name, no other information
• No Github star number
• ...

It is easier to check the information of a package by aggregating Dependency and github information in an API-like way,

Npm registry api

Npm official api (opens in a new tab) support CORS (opens in a new tab)

For example, Fetching next package information with the URL https://registry.npmjs.org/next/latest (opens in a new tab), and this is the simple result

{
  "name": "next",
  "version": "12.2.5",
  "description": "The React Framework",
  "repository": { "type": "git", "url": "git+https://github.com/vercel/next.js.git" },
  "homepage": "https://nextjs.org",
  "dependencies": { "@next/env": "12.2.5", "@swc/helpers": "0.4.3" }
}

We can get the version, repository address, dependencies and other information from this simple result.

Github api

You can fetch github information through its official api.

• restful (opens in a new tab)
• graphql (opens in a new tab)

Github api doesn’t support CORS (opens in a new tab), and there is a rate limit. Restful only has 60 requests per hour without the github authorization. Graphql must be logged in to use.

Fetch Github Document

Getting information by fetching Github document like a web crawler.

This method does not support CORS (opens in a new tab).

For example:

First, get the git repository document for nextjs by the url https://github.com/vercel/next.js.

Second, parse out document result via DOMParser (opens in a new tab)(in browse) or jsdom (opens in a new tab)(in nodejs), and then get data from dom element . For example, the text content of the #repo-stars-counter-star element is the stars count of the repository.

PDJ

PDJ is a tool that aggregates information about an npm package, it extracts the information and displays only the basic information about a package:.

• Introduction
• npm weekly downloads
• github star count
• Denpendency list, including the description of each dependent package

PDJ has a Web App (opens in a new tab) and also a Chrome extension (opens in a new tab). The Chrome extension supports checking the package.json on a github page to display the above mentioned information.