Angular - 'Could not find HammerJS'

In your package.json file add this to dependencies

"hammerjs": "^2.0.8",

Or if you want an alternative automatic way just you can type npm i hammerjs --save (or npm i hammerjs@2.0.8 --save if you want, since 2.0.8 is the latest version nowdays) in your root project folder and test then, if the problem still occurring try to delete the node_modules folder and reinstall it in the root project folder also by running npm install which will check the dependencies (where hammerjs resides), devDependencies ..., in package.json file and install them.

Also in your polyfills.ts (recommended to have a one if you have not)

import 'hammerjs/hammer';

Thus, it would be found while your angular app is executed since polyfills.ts itself is called by import (in a normal case, else you can check it) in main.ts which is the angular apps' entry point.

Install hammerjs

• with npm

  npm install --save hammerjs

• (or) with yarn

  yarn add hammerjs

Then import hammerjs on your app's entry point (e.g. src/main.ts).

import 'hammerjs';

In your systemjs.config.js file you also need to add the following entry:

'hammerjs': 'npm:hammerjs/hammer.js',

along with of course:

'@angular/material': 'npm:@angular/material/bundles/material.umd.js',

The other thing that's missing from your code (at least based on what you have in the GH repo) is the inclusion of the Material Design CSS, add this to your index.html file:

<link href="https://rawgit.com/angular/material2-builds/master/core/theming/prebuilt/indigo-pink.css" rel="stylesheet">

I hope this helps.