Angular2在焦点事件上添加类 [英] Angular2 on focus event to add class

问题描述

我正在考虑将Angular 1应用更新为Angular 2，并且我的旧指令存在问题。

I'm looking to update an Angular 1 app to Angular 2 and am having an issue with one of my old directives.

这个想法很简单。当聚焦输入字段时，应添加一个类（md-input-focus），另一个类被删除（md-input-wrapper）。然后这个过程应该在模糊事件上反转 - 即焦点丢失。

The idea is simple. When an input field is focused a class should be added (md-input-focus) and another be removed (md-input-wrapper). Then this process should be reversed on "blur" event - i.e. focus lost.

我的旧指令只包括行

.directive('mdInput',[
    '$timeout',
    function ($timeout) {
        return {
            restrict: 'A',
            scope: {
                ngModel: '='
            },
            link: function (scope, elem, attrs) {
                var $elem = $(elem);
                $elem.on('focus', function() {
                      $elem.closest('.md-input-wrapper').addClass('md-input-focus')
                })
                .on('blur', function() {
                 $(this).closest('.md-input-wrapper').removeClass('md-input-focus');
                })
             }

等...

我显然对我的指令有经典的开始，但已经耗尽了......技能

I obviously have the classic start to my directive but have run out of.....skill

import {Directive, ElementRef, Renderer, Input} from 'angular2/core';

@Directive({
      selector: '.mdInput',

})

export class MaterialDesignDirective {
      constructor(el: ElementRef, renderer: Renderer) {
           // Insert inciteful code here to do the above
      }
}

任何帮助都将不胜感激。

Any help would be appreciated.

更新：

HTML看起来像（在输入元素聚焦之前）：

The HTML would look like (before the input element was focused):

<div class="md-input-wrapper">
   <input type="text" class="md-input">
</div>

然后

<div class="md-input-wrapper md-input-focus">
   <input type="text" class="md-input">
</div>

之后。

输入元素是唯一一个可以接收焦点事件（因此指令的目标），但父< div> 需要添加和删除类。

The input element is the only one which can receive a focus event (and therefore the target for the directive) however the parent <div> requires the class addition and removal.

进一步的帮助

请参阅Plunker寻求帮助/解释 - 如果有人可以提供帮助会很棒

Please see Plunker for help/explanation - would be great if someone could help

推荐答案

更新

@Directive({selector: '.md-input', host: {
  '(focus)': 'setInputFocus(true)',
  '(blur)': 'setInputFocus(false)',
}})
class MaterialDesignDirective {
  MaterialDesignDirective(private _elementRef: ElementRef, private _renderer: Renderer) {}
  setInputFocus(isSet: boolean): void {
    this.renderer.setElementClass(this.elementRef.nativeElement.parentElement, 'md-input-focus', isSet);
  }
}

原始

这可以很容易地在没有 ElementRef 和 Renderer 的情况下完成（你是什么人）应该通过定义主机绑定来争取Angular2）：

This can easily be done without ElementRef and Renderer (what you should strive for in Angular2) by defining host bindings:

import {Directive, ElementRef, Renderer, Input} from 'angular2/core';

@Directive({
      selector: '.mdInput',
      host: {
        '(focus)':'_onFocus()',
        '(blur)':'_onBlur()',
        '[class.md-input-focus]':'inputFocusClass'
      }

})

export class MaterialDesignDirective {
      inputFocusClass: bool = false;

      _onFocus() {
        this.inputFocusClass = true;
      }

      _onBlur() {
        this.inputFocusClass = false;
      }
}

或者更简洁

@Directive({
      selector: '.mdInput',
      host: {
        '(focus)':'_setInputFocus(true)',
        '(blur)':'_setInputFocus(false)',
        '[class.md-input-focus]':'inputFocusClass'
      }

})

export class MaterialDesignDirective {
      inputFocusClass: bool = false;

      _setInputFocus(isFocus:bool) {
        this.inputFocusClass = isFocus;
      }
}

我只在Dart尝试过它工作正常。我希望我把它正确地翻译成TS。

I tried it only in Dart where it works fine. I hope I translated it correctly to TS.

不要忘记将类添加到指令：您使用该指令的元素。

Don't forget to add the class to the directives: of the element where you use the directive.

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