如何编写angular指令，通过选择器来切换类

好的，在阅读了你的赏金评论后，我明白你希望这是独立于控制器的。我花了一些时间彻底修改我的解决方案，我想我终于找到了一种方法来实现你想要的。

可以归结为两件事:

1)检测复选框:checked状态的变化，和

2)检测复选框:disabled状态变化

检测1)很容易，因为您可以使用一个简单的jQuery更改处理程序，但是检测2)需要更多的研究。它要求在子ng-disabled属性上使用scope.$watch。

下面是如何工作的演示:

var app = angular.module("myApp", [])
  .directive("classWhen", function() {
    function setClasses(classWhen, $element, $input) {
      Object.keys(classWhen).forEach(function(key) {
        var test = classWhen[key];
        // .toggleClass("className", true) === .addClass("className")
        // .toggleClass("className", false) === .removeClass("className")
        $element.toggleClass(key, $element.is(test));
      });
    }
    return {
      restrict: 'A',
      link: function link (scope, element, attrs) {
        var classWhen = JSON.parse(attrs.classWhen);
        var $element = $(element);
        $element.find("*").each(function (index, elem) {
          var $elem = $(this);
          // namespace the change event so we can easily .off() it
          $elem.off("change.classWhen");
          $elem.on("change.classWhen", function () {
            setClasses(classWhen, $element, $elem);
          });
          // watch child ng-disabled attribute
          scope.$watch($elem.attr("ng-disabled"), function (val) {
            setClasses(classWhen, $element, $elem);
          });
        });
      }
    };
  });

.is-checked {
  background-color: yellow;
}
.is-disabled {
  background-color: lightblue;
}

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div ng-app="myApp">
  <label>
    <input type="checkbox" ng-model="disableAll" />Disable All</label>
  <br>
  <br>
  <label class-when='{"is-checked": ":has(input:checked)", "is-disabled": ":has(input:disabled)"}'>
    <input type="checkbox" ng-disabled="disableAll">Example checkbox 1
  </label>
  <br>
  <label class-when='{"is-checked": ":has(input:checked)", "is-disabled": ":has(input:disabled)"}'>
    <input type="checkbox" ng-disabled="disableAll">Example checkbox 2
  </label>
  <br>
  <label class-when='{"is-checked": ":has(input:checked, .test)", "is-disabled": ":has(input:disabled)"}'>
    <input type="text" ng-disabled="disableAll" ng-class="testingClass" ng-model="testingClass"/>
    <br>
    <input type="checkbox" ng-disabled="disableAll">
    Example checkbox 3
  </label>
  <br>
  <label class-when='{"is-checked": ":has(input:checked)", "is-disabled": ":has(input:disabled)"}'>
    <input type="checkbox" ng-disabled="disableAll">Example checkbox 4
  </label>
</div>

这是我试图用通用的方式解决你的问题:https://plnkr.co/edit/kVyJQClmQhF3FeBTmKaX?p=preview

指令代码:

app.directive('classWhen', () => (scope, element, attrs) => {
  scope.$watchCollection(getClasses, setClasses)
  function getClasses() {
    // We have to evaluate expression in attrs.classWhen so that we get object
    const rawClasses = scope.$eval(attrs.classWhen)
    const classes = {}
    // then we normalize it so that strings are treated as jquery selectors
    Object.keys(rawClasses).forEach((className) => {
      const expr = rawClasses[className]
      classes[className] = typeof expr === 'string'
        ? element.is(expr)
        : !!expr // we normalize falsy values to booleans
    })
    // then we return it to $watchCollection
    return classes
  }
  /**
   * will be called whenever any of the classes changes
   */
  function setClasses(classes) {
    Object.keys(classes).forEach((className) => {
      element.toggleClass(className, classes[className])
    })
  }
})

我已经创建了一个通用的小提琴，也与RequireJS作为你使用。

请看这里

注意:无论你在选择器中添加了什么属性，如:checked和:disabled，将相关的角属性添加到子元素中，如ng-model和ng-disabled。它会像一个魅力!!

var app = window.app = angular.module("myApp", []);
define('classWhenDirective', function () {
    //var _ = require('lodash');
    var app = window.app;debugger;
    app.directive("classWhen", function() {
    return {
    restrict: 'A',
    link: function(scope, element, attrs) {
          scope.$watch(getChanges, setClasses)
  function getChanges() {
    var attrs = [];
    
    function getAttrs(elm) {
       $.each(elm.attributes, function(i, attrib){
     var name = attrib.name;
     var value = attrib.value;
       if(value && name.indexOf('ng-') > -1) {
         value = scope.$eval(value);
       }
     if(value) {      
       attrs.push(name + ':' + value);
     }
  });
     
    }
    
    getAttrs(element.get(0));
    
    element.children().each(function(){
       getAttrs(this);
    });
    
    return attrs.join(',');
  }
  function setClasses() {
    var rawClasses = scope.$eval(attrs.classWhen);
    Object.keys(rawClasses).forEach(function(className){
      var expr = rawClasses[className]
      var setClass = typeof expr === 'string'
        ? element.is(expr)
        : !!expr;
       element.toggleClass(className, setClass);
    });
  }
    }
  };   
    });
});
define('todo', ['classWhenDirective'], function() {
  var app = window.app;
  app.controller('myController', function($scope) {
  });
});
// angular bootstrap
require(['todo'], function() {
  angular.bootstrap(document, ['myApp']);
});

.is-checked {
  color: green;
}
.is-disabled {
  color: gray;
}

<script src="http://requirejs.org/docs/release/2.0.6/minified/require.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<h2>ClassWhen Directive</h2>
<div ng-controller="myController">
  <label>
    <input type="checkbox" ng-model="disableAll" />Disable All</label>
  <br>
  <br>
  <label class-when='{"is-checked": ":has(input:checked)", "is-disabled": ":has(input:disabled)"}'>
    <input type="checkbox" ng-model="checkBox1" ng-disabled="disableAll">ClassWhen checkbox 1
  </label>
  <br>
  <label class-when='{"is-checked": ":has(input:checked)", "is-disabled": ":has(input:disabled)"}'>
    <input type="checkbox" ng-model="checkBox2" ng-disabled="disableAll">ClassWhen checkbox 2
  </label>
</div>