Yarn versus Npm - “works on my machine” - clarification?

Question

Yarn versus Npm - “works on my machine” - clarification?

I am new to yarn and something caught my eye while reading this article that says:

Deterministic:
The same dependencies will be installed the same way through each machine, regardless of installation order. Yarn solves “Works on my machine” on issues related to version control and non-determinism using lockfiles and an installation algorithm that is deterministic and reliable

Question:

I do not understand: when I write npm install, he looks at package.jsonand installs the exact version, and each version also sets its dependencies according to its own package.json, etc. etc.

So what is the difference (regarding this aspect)

An example script will be evaluated for "a thing that may go differently from npm than yarn"

+6

javascript node.js npm yarnpkg

Royi namir Jan 01 '18 at 8:28

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1 answer

DevMonster · Accepted Answer · 2018-01-01T13:51:49+0000

The package.json file often contains the minimum version required for the dependency. For example, you could have "^ 1.0.0" which corresponds to version 1.0.0 or any minor releases.

{ "name": "my_package", "version": "1.0.0", "dependencies": { "my_dep": "^1.0.0" } }

When you run npm install, it can install version 1.0.0, 1.1.0, 1.2.0, etc. "my_dep" because all of these versions meet the requirements of package.json. Ultimately, you can use version 1.0.0 on your local computer and 1.1.0 in a test environment.

yarn.lock , , "my_dep" . - :

# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
# yarn lockfile v1
my_dep@^1.0.0:    
version "1.1.0"
resolved "https://registry.npmjs.org/my_dep/-/my_dep-1.1.0.tgz#a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0"

"my_dep" 1.1.0, (1.2.0).