ng2-encrm-components/components/dropdown/button-dropdown.component.ts

angular 2 components

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

@Component({
  selector: 'button-dropdown',
  template: require('./button-dropdown.component.html'),
  styles:   [require('./button-dropdown.component.scss')]
})
export class ButtonDropdownComponent {
  private isOpen: boolean = false;

  constructor(private _elementRef: ElementRef) {
  }

  /**
   * hides dropdown on outside click
   * @param target
   */
  @HostListener('document:click', ['$event.target']) documentClickHandler = (target) => {
    if (!this._elementRef.nativeElement.contains(target)) {
      this.hide();
    }
  };

  toggleShow() {
    this.isOpen = !this.isOpen;
    this.checkPosition();
  }

  hide() {
    this.isOpen = false;
    this.checkPosition();
  }

  /**
   * check position of menu and move if it is placed out of view window
   */
  checkPosition() {
    setTimeout(() => {
      let el   = this._elementRef.nativeElement.querySelector('[list]');
      if(!el){
        return;
      }
      let rect = el.getBoundingClientRect();
      if (rect.right > window.innerWidth) {
        let left: number = +el.style.left.slice(0, -2);
        el.style.left = left - (rect.right - window.innerWidth) - 20 + 'px';
      }
      if(rect.left < 0){
        let left: number = +el.style.left.slice(0, -2);
        el.style.left = left - rect.left + 5 + 'px';
      }
    }, 1);
  }

}