Package-lock.json - requires vs dependencies

Question

In package-lock.json in dependency object, I have both requires and dependencies fields, e.g

  "requires": {
    "@angular-devkit/core": "0.8.5",
    "rxjs": "6.2.2",
    "tree-kill": "1.2.0",
    "webpack-sources": "1.3.0"
  },
  "dependencies": {
    "rxjs": {
      "version": "6.2.2",
      "resolved": "https://registry.npmjs.org/rxjs/-/rxjs-6.2.2.tgz",
      "integrity": "sha512-0MI8+mkKAXZUF9vMrEoPnaoHkfzBPP4IGwUYRJhIRJF6/w3uByO1e91bEHn8zd43RdkTMKiooYKmwz7RH6zfOQ==",
      "dev": true,
      "requires": {
        "tslib": "1.9.3"
      }
    }
  }

What is the difference between these two? Why some dependencies are listed in requires, other in dependencies, and some of them in both of these fields?

score 40 · Accepted Answer · edited Dec 29 '20 at 06:41

By default, npm installs all packages directly in node_modules.

However, let's say that package X is dependent on package Z in version 1.0 and package Y is dependent on the same package Z, but in version 2.0. In this case we have to install two versions of this package. One will be installed in root node_modules folder, and another one will be installed in node_modules folder of dependant package, e.g.

package.json
node_modules
    /X
    /Y
        /node_modules
            /Z@2.0
    /Z@1.0

Equally likely, npm could build a different, but still correct, package tree:

package.json
node_modules
    /X
        /node_modules
            /Z@1.0
    /Y
    /Z@2.0

The package-lock.json file will attempt to describe not only the dependencies of your project, but this tree structure as well. Which of the two trees above to build will be encoded in the JSON.

With this knowledge, it's easy to understand:

"requires" reflects dependencies from package.json file of this dependency, while dependencies reflects actually installed dependencies in node_modules folder of this dependency.

Compared to ruby's Gemfile.lock, allowing multiple versions of the same package to be used together is much more complex. It is a little difficult to justify its benefit. — rocksoccer, Jun 25 '19 at 17:34
Not needing a SAT solver to install packages safely is nice. Another win here is that installing a new package should never change the functionality of existing ones. Its all trade-offs. — meawoppl, Jul 02 '20 at 20:50

score 29 · Answer 2 · edited Jan 27 '22 at 06:30

After reading the answers above, maybe I can put it more simply:

requires can be shared among all other top levels dependencies, while dependencies are standalone, belonging only to the module requiring them.

i.e.

"@angular-devkit/core": "0.8.5","tree-kill": "1.2.0", and "webpack-sources": "1.3.0" do not belong only to the module. They are in the same level as the module requiring them. By contrast, "rxjs": "6.2.2" exists exclusively due to the module requiring it, and it is used only by that module.

Package-lock.json - requires vs dependencies

2 Answers2

Linked