With package.json in place, we can now choose the Gulp module(s) we need in order to auto-task our development work. This is usually done with the command npm i -D MODULE: install MODULE and save it for use during -Development. (The long form of npm i -D MODULE is npm install --save-dev MODULE.)
MODULE is the name of a Gulp module we’d invoke in a task. As an example, let’s use gulp-htmlmin, which is a module that compresses HTML files. In the same folder in which package.json was created, let’s run:
npm i -D gulp-htmlmin(If you received an access error, type sudo npm i -D gulp-htmlmin.)
This will search for gulp-htmlmin in the NPM registry, then, if found, download the gulp-htmlmin module into a folder called node_modules. If node_modules doesn’t exist, this module will create it. (Every first module fetched from the registry will create node_modules if node_modules isn’t found.)
If you open package.json, you’ll note that a new object called devDependencies was added with a member whose name is "gulp-htmlmin" and whose value is "^5.0.1" ("gulp-htmlmin": "^5.0.1"). This means that the versions of gulp-htmlmin that will be used range from 5.0.1 → 6.0.0, inclusive and exclusive, respectively. (Read more at https://docs.npmjs.com/misc/semver#caret-ranges-123-025-004.)
Let’s also install a local version of Gulp:
npm i -D gulp(Again, if you received an access error, type sudo npm i -D gulp.)
Note the new gulp member object in devDependencies.
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