Angular 5 and underscore library

Are you missing the underscore library in your most recent Angular 5 project?

It is easier than you may think - the only you need to do is just add two dependencies to your package.json file.

Step 1. Install dependencies

You can do this with npm command.

npm install --save @types/underscore

and next

npm install --save underscore

Step 2. Use it

In order to use underscore library in your component or service class you have to import library in the following way:

import * as _ from "underscore";

That is basically all - now you can take all the goodies from underscore. For example, to fetch all unique key values from an array of key-value struct we can do this way:

public uniqueKeys(input: {[key: string]: string}[]): string[] {

   let keys = _
     .chain(input)
     .map(a => _.keys(a))
     .flatten()
     .uniq(false)
     .value()