Angular 2
direktiven

Syntax

• <input [value]="value"> - Binder attributvärde klassmedlem name .

• <div [attr.data-note]="note"> - Binder data-note till variabel note .

• <p green></p> - Anpassat direktiv

Anmärkningar

Attributdirektiv

<div [class.active]="isActive"></div>

<span [style.color]="'red'"></span>

<p [attr.data-note]="'This is value for data-note attribute'">A lot of text here</p>

Komponent är ett direktiv med mall

import { Component } from '@angular/core';
@Component({
  selector: 'my-app',
  template: `
    <h1>Angular 2 App</h1>
    <p>Component is directive with template</p>
  `
})
export class AppComponent {
}

Strukturdirektiv

<div *ngFor="let item of items">{{ item.description }}</div>

<span *ngIf="isVisible"></span>

Anpassat direktiv

import {Directive, ElementRef, Renderer} from '@angular/core';

@Directive({
  selector: '[green]',
})

class GreenDirective {
  constructor(private _elementRef: ElementRef, 
              private _renderer: Renderer) {
    _renderer.setElementStyle(_elementRef.nativeElement, 'color', 'green');
  }
}

Användande:

<p green>A lot of green text here</p>

* ngFor

form1.component.ts:

import { Component } from '@angular/core';

// Defines example component and associated template
@Component({
    selector: 'example',
    template: `
      <div *ngFor="let f of fruit"> {{f}} </div>
      <select required>
        <option *ngFor="let f of fruit" [value]="f"> {{f}} </option>
      </select>
    `
})

// Create a class for all functions, objects, and variables
export class ExampleComponent { 
    // Array of fruit to be iterated by *ngFor
    fruit = ['Apples', 'Oranges', 'Bananas', 'Limes', 'Lemons'];
}

Produktion:

<div>Apples</div>
<div>Oranges</div>
<div>Bananas</div>
<div>Limes</div>
<div>Lemons</div>
<select required>
  <option value="Apples">Apples</option>
  <option value="Oranges">Oranges</option>
  <option value="Bananas">Bananas</option>
  <option value="Limes">Limes</option>
  <option value="Lemons">Lemons</option>
</select>

I sin mest enkla form har *ngFor två delar: let variableName of object/array

För fruit = ['Apples', 'Oranges', 'Bananas', 'Limes', 'Lemons']; ,

Äpplen, apelsiner, och så vidare är de värden inne i matrisen fruit .

[value]="f" kommer att vara lika med varje aktuell fruit ( f ) som *ngFor har itererat över.

Till skillnad från AngularJS har Angular2 inte fortsatt med användningen av ng-options för <select> och ng-repeat för alla andra allmänna upprepningar.

*ngFor är mycket lik ng-repeat med något varierad syntax.

referenser:

Angular2 | Visar data

Angular2 | ngFor

Angular2 | formulär

Kopiera till Urklippsdirektiv

I det här exemplet kommer vi att skapa ett direktiv för att kopiera en text till urklippet genom att klicka på ett element

kopierings-text.directive.ts

import {
    Directive,
    Input,
    HostListener
} from "@angular/core";

@Directive({
    selector: '[text-copy]'
})
export class TextCopyDirective {

    // Parse attribute value into a 'text' variable
    @Input('text-copy') text:string;

    constructor() {
    }


    // The HostListener will listen to click events and run the below function, the HostListener supports other standard events such as mouseenter, mouseleave etc.
    @HostListener('click') copyText() {

        // We need to create a dummy textarea with the text to be copied in the DOM
        var textArea = document.createElement("textarea");

        // Hide the textarea from actually showing
        textArea.style.position = 'fixed';
        textArea.style.top = '-999px';
        textArea.style.left = '-999px';
        textArea.style.width = '2em';
        textArea.style.height = '2em';
        textArea.style.padding = '0';
        textArea.style.border = 'none';
        textArea.style.outline = 'none';
        textArea.style.boxShadow = 'none';
        textArea.style.background = 'transparent';

        // Set the texarea's content to our value defined in our [text-copy] attribute
        textArea.value = this.text;
        document.body.appendChild(textArea);

        // This will select the textarea
        textArea.select();

        try {
            // Most modern browsers support execCommand('copy'|'cut'|'paste'), if it doesn't it should throw an error
            var successful = document.execCommand('copy');
            var msg = successful ? 'successful' : 'unsuccessful';
            // Let the user know the text has been copied, e.g toast, alert etc.
            console.log(msg);
        } catch (err) {
            // Tell the user copying is not supported and give alternative, e.g alert window with the text to copy
            console.log('unable to copy');
        }

        // Finally we remove the textarea from the DOM
        document.body.removeChild(textArea);
    }
}

export const TEXT_COPY_DIRECTIVES = [TextCopyDirective];

något-page.component.html

Kom ihåg att injicera TEXT_COPY_DIRECTIVES i direktiven för din komponent

...
    <!-- Insert variable as the attribute's value, let textToBeCopied = 'http://facebook.com/' -->
    <button [text-copy]="textToBeCopied">Copy URL</button>
    <button [text-copy]="'https://www.google.com/'">Copy URL</button>
...

Testa ett anpassat direktiv

Får ett direktiv som belyser text om mushändelser

import { Directive, ElementRef, HostListener, Input } from '@angular/core';

@Directive({ selector: '[appHighlight]' })
export class HighlightDirective {
  @Input('appHighlight') // tslint:disable-line no-input-rename
  highlightColor: string;

  constructor(private el: ElementRef) { }

  @HostListener('mouseenter')
  onMouseEnter() {
    this.highlight(this.highlightColor || 'red');
  }

  @HostListener('mouseleave')
  onMouseLeave() {
    this.highlight(null);
  }

  private highlight(color: string) {
    this.el.nativeElement.style.backgroundColor = color;
  }
}

Det kan testas så här

import { ComponentFixture, ComponentFixtureAutoDetect, TestBed } from '@angular/core/testing';

import { Component } from '@angular/core';
import { HighlightDirective } from './highlight.directive';

@Component({
  selector: 'app-test-container',
  template: `
    <div>
      <span id="red" appHighlight>red text</span>
      <span id="green" [appHighlight]="'green'">green text</span>
      <span id="no">no color</span>
    </div>
  `
})
class ContainerComponent { }

const mouseEvents = {
  get enter() {
    const mouseenter = document.createEvent('MouseEvent');
    mouseenter.initEvent('mouseenter', true, true);
    return mouseenter;
  },
  get leave() {
    const mouseleave = document.createEvent('MouseEvent');
    mouseleave.initEvent('mouseleave', true, true);
    return mouseleave;
  },
};

describe('HighlightDirective', () => {
  let fixture: ComponentFixture<ContainerComponent>;
  let container: ContainerComponent;
  let element: HTMLElement;

  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [ContainerComponent, HighlightDirective],
      providers: [
        { provide: ComponentFixtureAutoDetect, useValue: true },
      ],
    });

    fixture = TestBed.createComponent(ContainerComponent);
    // fixture.detectChanges(); // without the provider
    container = fixture.componentInstance;
    element = fixture.nativeElement;
  });

  it('should set background-color to empty when mouse leaves with directive without arguments', () => {
    const targetElement = <HTMLSpanElement>element.querySelector('#red');

    targetElement.dispatchEvent(mouseEvents.leave);
    expect(targetElement.style.backgroundColor).toEqual('');
  });

  it('should set background-color to empty when mouse leaves with directive with arguments', () => {
    const targetElement = <HTMLSpanElement>element.querySelector('#green');

    targetElement.dispatchEvent(mouseEvents.leave);
    expect(targetElement.style.backgroundColor).toEqual('');
  });

  it('should set background-color red with no args passed', () => {
    const targetElement = <HTMLSpanElement>element.querySelector('#red');

    targetElement.dispatchEvent(mouseEvents.enter);
    expect(targetElement.style.backgroundColor).toEqual('red');
  });

  it('should set background-color green when passing green parameter', () => {
    const targetElement = <HTMLSpanElement>element.querySelector('#green');

    targetElement.dispatchEvent(mouseEvents.enter);
    expect(targetElement.style.backgroundColor).toEqual('green');
  });
});