等效于hasAttribute()的AngularJS? [英] AngularJS equivalent for hasAttribute()?

问题描述

在指令中，我想在元素上执行某些功能之前检查元素是否具有属性.但是在 jqLit​​e文档中，我看不到有什么用.

In a directive, I want to check if an element has an attribute before I execute some function on it. But I don't see anything made for that in the jqLite docs.

例如:

.directive('noReadonly', function() {

    return {
      link: function($scope, $element, $attr, ctrl) {

        $element.on('focus', function() {
          if ($element.hasAttribute('readonly'))
          $element.removeAttr('readonly');
        });

      },
    }
  })

推荐答案

$attr是具有属性的对象，因此您可以像普通方法一样使用它:

$attr is a object with the attributes, so you can work with it like normal:

if($attr.hasOwnProperty("readonly"))

如注释中所述，这将检查该属性是否存在.该元素将导致真实的响应:

As mentioned in the comments, this checks that the property exists. This element would result in a true response:

<input name="test" readonly>

如果您还想检查真实值，则可以扩展逻辑:

If you want to also check for truthy values, you can extend the logic:

if($attr.hasOwnProperty("readonly") && $attr.readonly) {}

请注意，属性值被解析为字符串，因此$attr.readonly等于"true"(字符串)而不是true(布尔值).

Note that attribute values are parsed as strings, so $attr.readonly equals "true" (String) and not true (Boolean).

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