Creating A Simple Copy-To-Clipboard Directive In Angular 2.4.9

// Import the core angular services.
import { DOCUMENT } from "@angular/platform-browser";
import { Inject } from "@angular/core";
import { Injectable } from "@angular/core";

@Injectable()
export class ClipboardService {

	private dom: Document;


	// I initialize the Clipboard service.
	// --
	// CAUTION: This service is tightly couped to the browser DOM (Document Object Model).
	// But, by injecting the "document" reference rather than trying to reference it
	// globally, we can at least pretend that we are trying to lower the tight coupling.
	constructor( @Inject( DOCUMENT ) dom: Document ) {

		this.dom = dom;

	}


	// ---
	// PUBLIC METHODS.
	// ---


	// I copy the given value to the user's system clipboard. Returns a promise that
	// resolves to the given value on success or rejects with the raised Error.
	public copy( value: string ) : Promise<string> {

		var promise = new Promise(
			( resolve, reject ) : void => {

				var textarea = null;

				try {

					// In order to execute the "Copy" command, we actually have to have
					// a "selection" in the currently rendered document. As such, we're
					// going to inject a Textarea element and .select() it in order to
					// force a selection.
					// --
					// NOTE: This Textarea is being rendered off-screen.
					textarea = this.dom.createElement( "textarea" );
					textarea.style.height = "0px";
					textarea.style.left = "-100px";
					textarea.style.opacity = "0";
					textarea.style.position = "fixed";
					textarea.style.top = "-100px";
					textarea.style.width = "0px";
					this.dom.body.appendChild( textarea );

					// Set and select the value (creating an active Selection range).
					textarea.value = value;
					textarea.select();

					// Ask the browser to copy the current selection to the clipboard.
					this.dom.execCommand( "copy" );

					resolve( value );

				} finally {

					// Cleanup - remove the Textarea from the DOM if it was injected.
					if ( textarea && textarea.parentNode ) {

						textarea.parentNode.removeChild( textarea );

					}

				}

			}
		);

		return( promise );

	}

}

// Import the core angular services.
import { Directive } from "@angular/core";
import { EventEmitter } from "@angular/core";

// Import the application components and services.
import { ClipboardService } from "./clipboard.service";

// This directive acts as a simple glue layer between the given [clipboard] property
// and the underlying ClipboardService. Upon the (click) event, the [clipboard] value
// will be copied to the ClipboardService and a (clipboardCopy) event will be emitted.
@Directive({
	selector: "[clipboard]",
	inputs: [ "value: clipboard" ],
	outputs: [
		"copyEvent: clipboardCopy",
		"errorEvent: clipboardError"
	],
	host: {
		"(click)": "copyToClipboard()"
	}
})
export class ClipboardDirective {

	public copyEvent: EventEmitter<string>;
	public errorEvent: EventEmitter<Error>;
	public value: string;

	private clipboardService: ClipboardService;


	// I initialize the clipboard directive.
	constructor( clipboardService: ClipboardService ) {

		this.clipboardService = clipboardService;
		this.copyEvent = new EventEmitter();
		this.errorEvent = new EventEmitter();
		this.value = "";

	}


	// ---
	// PUBLIC METODS.
	// ---


	// I copy the value-input to the Clipboard. Emits success or error event.
	public copyToClipboard() : void {

		this.clipboardService
			.copy( this.value )
			.then(
				( value: string ) : void => {

					this.copyEvent.emit( value );

				}
			)
			.catch(
				( error: Error ) : void => {

					this.errorEvent.emit( error );

				}
			)
		;

	}

}

// Import the core angular services.
import { Component } from "@angular/core";

@Component({
	moduleId: module.id,
	selector: "my-app",
	styleUrls: [ "./app.component.css" ],
	template:
	`
		<p>
			<button
				[clipboard]="value1.innerHTML.trim()"
				(clipboardCopy)="logSuccess( $event )"
				(clipboardError)="logError( $event )">
				Copy Text
			</button>

			<span #value1>
				Hello World!
			</span>
		</p>

		<p>
			<button
				[clipboard]="value2.innerHTML.trim()"
				(clipboardCopy)="logSuccess( $event )"
				(clipboardError)="logError( $event )">
				Copy Text
			</button>

			<span #value2>
				Rock on With Yer Bad Self!
			</span>
		</p>

		<p>
			<button
				[clipboard]="value3.innerHTML.trim()"
				(clipboardCopy)="logSuccess( $event )"
				(clipboardError)="logError( $event )">
				Copy Text
			</button>

			<span #value3>
				Weeezing The Ju-uice!
			</span>
		</p>

		<textarea
			#tester
			(click)="tester.select()"
			placeholder="Test your Copy operation here..."
		></textarea>
	`
})
export class AppComponent {

	// I initialize the app component.
	constructor() {
		// ...
	}


	// ---
	// PUBLIC METODS.
	// ---


	// I log Clipboard "copy" errors.
	public logError( error: Error ) : void {

		console.group( "Clipboard Error" );
		console.error( error );
		console.groupEnd();

	}


	// I log Clipboard "copy" successes.
	public logSuccess( value: string ) : void {

		console.group( "Clipboard Success" );
		console.log( value );
		console.groupEnd();

	}

}