How to install necessary packages by `npm install` - npm

Question

I have the following in package.json.
{
"private": true,
"devDependencies": {
"gulp": "^3.8.8"
},
"dependencies": {
"laravel-elixir": "^4.0.0",
"bootstrap-sass": "^3.0.0"
}
}
After running npm install when I check node_modules, there are a lot of packages are installed. from .bin, abbrev to yeast. I think there are more than 200 packages. I thought npm installs only necessary packages including dependencies.
Q1: How can I avoid installing unnecessary packages and installing only necessary packages. Can I do it? Or do I need all packages?
Q2: Does npm install all npm packages?

Answer 1

Summary:
Q1: How can I avoid installing unnecessary packages and installing
only necessary packages. Can I do it? Or do I need all packages?
You are installing all dependencies required by the dependencies of your module (modules requiring modules).
Q2: Does npm install all npm packages?
No.
In depth:
You installed gulp. Here are gulp's dependencies:
"dependencies": {
"archy": "^1.0.0",
"chalk": "^1.0.0",
"deprecated": "^0.0.1",
"gulp-util": "^3.0.0",
"interpret": "^1.0.0",
"liftoff": "^2.1.0",
"minimist": "^1.1.0",
"orchestrator": "^0.3.0",
"pretty-hrtime": "^1.0.0",
"semver": "^4.1.0",
"tildify": "^1.0.0",
"v8flags": "^2.0.2",
"vinyl-fs": "^0.3.0"
}
archy has the following dependencies:
"dependencies": {
"ansi-styles": "^2.1.0",
"escape-string-regexp": "^1.0.2",
"supports-color": "^3.1.2"
},
interpret (still going through gulp dependencies) has the following dependencies:
"dependencies": {
"extend": "^2.0.1",
"findup-sync": "^0.3.0",
"flagged-respawn": "^0.3.1",
"rechoir": "^0.6.0",
"resolve": "^1.1.6"
}
liftoff has the following dependencies:
"dependencies": {
"extend": "^2.0.1",
"findup-sync": "^0.3.0",
"flagged-respawn": "^0.3.1",
"rechoir": "^0.6.0",
"resolve": "^1.1.6"
}
orchestrator requires the following dependencies:
"dependencies": {
"end-of-stream": "~0.1.5",
"sequencify": "~0.0.7",
"stream-consume": "~0.1.0"
},
...
In short... The bigger, more dependent module you install, the more dependencies are required. It's not always a bad thing. I recommend installing only what is needed to get the job you need done (sometimes it's a lot, sometimes not).
UPDATE
I just noticed that gulp was a dev-dependency... Moving on to elixir non-dev dependencies:
"dependencies": {
"babelify": "^7.2.0",
"browser-sync": "^2.7.10",
"browserify": "^11.2.0",
"del": "^1.2.0",
"glob": "^5.0.14",
"gulp-autoprefixer": "^2.3.1",
"gulp-babel": "^6.1.0",
"babel-preset-es2015": "^6.1.0",
"babel-preset-react": "^6.1.18",
"gulp-batch": "^1.0.5",
"gulp-coffee": "^2.3.1",
"gulp-concat": "^2.6.0",
"gulp-cssnano": "^2.0.0",
"gulp-if": "^1.2.5",
"gulp-less": "^3.0.3",
"gulp-load-plugins": "^1.0.0-rc.1",
"gulp-notify": "^2.2.0",
"gulp-phpspec": "^0.5.3",
"gulp-phpunit": "0.11.x",
"gulp-rename": "^1.2.2",
"gulp-rev": "^5.1.0",
"gulp-rev-replace": "^0.4.2",
"gulp-sass": "^2.0.3",
"gulp-sourcemaps": "^1.5.2",
"gulp-shell": "^0.5.0",
"gulp-uglify": "^1.4.2",
"gulp-util": "^3.0.6",
"gulp-watch": "^4.2.4",
"insert-css": "^0.2.0",
"merge-stream": "^0.1.8",
"parse-filepath": "^0.5.0",
"partialify": "^3.1.3",
"path": "^0.11.14",
"require-dir": "^0.3.0",
"run-sequence": "^1.1.1",
"underscore": "^1.8.3",
"underscore-deep-extend": "0.0.5",
"vinyl-buffer": "^1.0.0",
"vinyl-paths": "^1.0.0",
"vinyl-source-stream": "^1.1.0",
"watchify": "^3.2.3"
},
...