The ngHide
directive shows or hides the given HTML element based on the expression
provided to the ngHide
attribute. The element is shown or hidden by removing or adding
the ng-hide
CSS class onto the element. The .ng-hide
CSS class is predefined
in AngularJS and sets the display style to none (using an !important flag).
For CSP mode please add angular-csp.css
to your html file (see ngCsp).
<!-- when $scope.myValue is truthy (element is hidden) -->
<div ng-hide="myValue" class="ng-hide"></div>
<!-- when $scope.myValue is falsy (element is visible) -->
<div ng-hide="myValue"></div>
When the ngHide
expression evaluates to a truthy value then the .ng-hide
CSS class is added to the class
attribute on the element causing it to become hidden. When falsy, the .ng-hide
CSS class is removed
from the element causing the element not to appear hidden.
You may be wondering why !important is used for the .ng-hide
CSS class. This is because the .ng-hide
selector
can be easily overridden by heavier selectors. For example, something as simple
as changing the display style on a HTML list item would make hidden elements appear visible.
This also becomes a bigger issue when dealing with CSS frameworks.
By using !important, the show and hide behavior will work as expected despite any clash between CSS selector specificity (when !important isn't used with any conflicting styles). If a developer chooses to override the styling to change how to hide an element then it is just a matter of using !important in their own CSS code.
.ng-hide
By default, the .ng-hide
class will style the element with display: none!important
. If you wish to change
the hide behavior with ngShow/ngHide then this can be achieved by restating the styles for the .ng-hide
class in CSS:
.ng-hide {
/* this is just another form of hiding an element */
display: block!important;
position: absolute;
top: -9999px;
left: -9999px;
}
By default you don't need to override in CSS anything and the animations will work around the display style.
ngHide
Animations in ngShow/ngHide work with the show and hide events that are triggered when the directive expression
is true and false. This system works like the animation system present with ngClass, except that the .ng-hide
CSS class is added and removed for you instead of your own CSS class.
//
//a working example can be found at the bottom of this page
//
.my-element.ng-hide-add, .my-element.ng-hide-remove {
transition: 0.5s linear all;
}
.my-element.ng-hide-add { ... }
.my-element.ng-hide-add.ng-hide-add-active { ... }
.my-element.ng-hide-remove { ... }
.my-element.ng-hide-remove.ng-hide-remove-active { ... }
Keep in mind that, as of AngularJS version 1.3.0-beta.11, there is no need to change the display property to block during animation states--ngAnimate will handle the style toggling automatically for you.
<ANY
ng-hide="expression">
...
</ANY>
removeClass: .ng-hide
- happens after the ngHide
expression evaluates to a truthy value and just before the contents are set to hidden
addClass: .ng-hide
- happens after the ngHide
expression evaluates to a non truthy value and just before the contents are set to visible
Param | Type | Details |
---|---|---|
ngHide | expression |
If the expression is truthy then the element is shown or hidden respectively. |
Click me: <input type="checkbox" ng-model="checked" aria-label="Toggle ngShow"><br/>
<div>
Show:
<div class="check-element animate-hide" ng-show="checked">
<span class="glyphicon glyphicon-thumbs-up"></span> I show up when your checkbox is checked.
</div>
</div>
<div>
Hide:
<div class="check-element animate-hide" ng-hide="checked">
<span class="glyphicon glyphicon-thumbs-down"></span> I hide when your checkbox is checked.
</div>
</div>
@import url(../../components/bootstrap-3.1.1/css/bootstrap.css);
.animate-hide {
transition: all linear 0.5s;
line-height: 20px;
opacity: 1;
padding: 10px;
border: 1px solid black;
background: white;
}
.animate-hide.ng-hide {
line-height: 0;
opacity: 0;
padding: 0 10px;
}
.check-element {
padding: 10px;
border: 1px solid black;
background: white;
}
var thumbsUp = element(by.css('span.glyphicon-thumbs-up'));
var thumbsDown = element(by.css('span.glyphicon-thumbs-down'));
it('should check ng-show / ng-hide', function() {
expect(thumbsUp.isDisplayed()).toBeFalsy();
expect(thumbsDown.isDisplayed()).toBeTruthy();
element(by.model('checked')).click();
expect(thumbsUp.isDisplayed()).toBeTruthy();
expect(thumbsDown.isDisplayed()).toBeFalsy();
});