hash-for-dep

What is hash-for-dep?

The hash-for-dep npm package is used to generate a hash for a given dependency in a Node.js project. This can be useful for caching, ensuring consistency, and detecting changes in dependencies.

What are hash-for-dep's main functionalities?

Generate Hash for a Dependency

This feature allows you to generate a hash for a specific dependency, such as 'express'. The hash can be used to detect changes or for caching purposes.

const hashForDep = require('hash-for-dep');
const hash = hashForDep('express');
console.log(hash);

Generate Hash for a Dependency with a Specific Version

This feature allows you to generate a hash for a specific version of a dependency. This can be useful for ensuring consistency across different environments.

const hashForDep = require('hash-for-dep');
const hash = hashForDep('express', '4.17.1');
console.log(hash);

Generate Hash for a Dependency with Options

This feature allows you to generate a hash for a dependency with additional options, such as specifying the base directory of the project. This can be useful for more complex project structures.

const hashForDep = require('hash-for-dep');
const options = { basedir: '/path/to/project' };
const hash = hashForDep('express', options);
console.log(hash);

Other packages similar to hash-for-dep

hash-sum

The hash-sum package generates a short, unique hash for any given input. It is simpler and more general-purpose compared to hash-for-dep, which is specifically designed for hashing dependencies.

crypto

The built-in Node.js crypto module can be used to generate hashes for various purposes. While it is more versatile and powerful, it requires more setup and is not specifically tailored for dependency hashing like hash-for-dep.

object-hash

The object-hash package generates a hash for JavaScript objects. It is useful for hashing complex objects but does not specifically target dependencies like hash-for-dep.

README

hash-for-dep

Generate a hash representing the stats of this module files and all its descendents files.

var hashForDep = require('hash-for-dep');

hashForDep('rsvp'); // if RSVP is a dependency of the current project, you will get a checksum for it
hashForDep('rsvp', 'path/to/other/project'); //  you will get a checksum for RSVP resolved relative to the provided root

What does Hash For Dep consider a dependency?

HashForDep respects the node resolution algorithim.

For example given:

foo/package.json
foo/index.js
foo/node_modules/a/
foo/node_modules/a/package.json
foo/node_modules/a/index.js
foo/node_modules/a/node_modules/b
foo/node_modules/a/node_modules/b/package.json
foo/node_modules/a/node_modules/b/index.js
foo/node_modules/a/node_modules/f
foo/node_modules/a/node_modules/f/index.js
foo/node_modules/a/node_modules/f/package.json
foo/node_modules/c
foo/node_modules/c/index.js
foo/node_modules/c/package.json
foo/node_modules/d
foo/node_modules/d/index.js
foo/node_modules/d/package.js

where foo/package.json depends on a and c but not d and foo/node_modules/a/package.json depends on b not f

HashForDep will consider: a c b as dependencies, and simply ignore d and f. When HashForDep considers a dependency, it will stat each of its files and those of its dependencies.

Cache

NOTE: By default, these hashes are cached for the life of the process. As this is the same strategy node uses for require(x) we can safely follow suit.

That being said, some scenarios may exist where this is not wanted. So just like require._cache exists, we provide the following options:

To evict the cache manually (maybe for testing)

require('hash-for-dep')._resetCache();

To opt out of the cache on a per invocation basis

var hashForDep = require('hash-for-dep');

hashForDep(name, path, null, false /* this mysterious argument should be set to false */);