Do you know why is the {{ project.title }} before I see the real value of the scope.
And how to solve that ?
EDIT : <title>{{ pageTitle }}</title>
Page is loading
Page completely loaded
Your views for Angular.JS apps are just static HTML. If you remove the script tag that references Angular.JS, you'd end up with a page full of curly brackets in plain sight that never get replaced.
When your browser finished loading Angular.JS and loading your application, the expressions in those curly brackets are evaluated. That's why you see, for a brief moment, {{…}} in your page title.
As noted by others, the ng-cloak directive is usually the way to get rid of the flickering before the app is fully loaded.
But since ng-cloak is just CSS, it cannot be applied to the page title. You'll need ng-bind for that, as noted here.
<title ng-bind="pageTitle">Default Title</title>
You should be showing the code, but in general it's probably because you aren't using ng-cloak https://docs.angularjs.org/api/ng/directive/ngCloak
However, in the case of the title, you need to use ng-bind=project.title instead <title>{{ project.title }}</title>
Check How to hide {{title}} in <title> tag while using AngularJS?
To prevent this, you should use ng-bind instead of {{ }} for the first screen of your app.
ng-bind is a directive that is added to an element attribute, so it is displayed only when the page is loaded.
According to the description of ngBind, we usually use {{ expression }} to replace ng-bind. But in a first-loading situation, image that you firstly load AngularJS(maybe in index.html), it'll show the original {{ }}. After that, it transits to what u need. To overcome it, you can use ngCloak or just use ng-bind in your first page.
OK, please check this ?
Related
I am slightly confused by this behaviour of Angular JS.
Angular.js' ng-if will not render an element if the expression evaluates to false, if the documents are anything to go by. I have this piece of code in my html template:
<div ng-if="false">
<img src="{{ imgPath }}" />
<p>This block is not rendered</p>
</div>
// In the controller
$scope.imgPath = "/invalid/image/path";
When this template is rendered, I cannot, as expected, see the img element or the p element on developer tools:
However... when I look at the network tab, there is a request to fetch the image:
I thought that if the element is not rendered, it wouldn't function in any way or form since it doesn't exist... Why does the browser fetch the image in this case?
You can see the working code on plnkr here, you'll have to hit F12 to watch the error on the console.
I know that using ng-src= {{ }} instead of src={{ }} would solve the issue of img src being fetched with unresolved expression before the data is bound, but, this question deals more with why ng-if isn't stopping the request in the first place
It takes AngularJS a small amount of time to process your markup. So, intially when your page loads, the browser does it's thing trying to process the markup. It sees this:
<div ng-if="false">
<img src="{{ imgPath }}" />
<p>This block is not rendered</p>
</div>
But, so far, AngularJS has not been loaded, and the AngularJS directives have no meaning. The browser attempts to load an image located at the literal URL of : {{ imgPath }}, which the URL encoder will translate to %7B%7B%20imgPath%20%7B%7B, which will fail (obviously). Still, AngularJS has not been loaded.
Once AngularJS finally loads, it goes through the DOM and applies the ngIf directive and removes the node.
This is why you want to use ngSrc. This will prevent the image request, since the browser doesn't understand the ng-src directive and won't treat it like a src attribute.
This tutorial demonstrates the use of the directive ngSrc instead of src :
<ul class="phones">
<li ng-repeat="phone in phones" class="thumbnail">
<img ng-src="{{phone.imageUrl}}">
</li>
</ul>
They ask to:
Replace the ng-src directive with a plain old src attribute.
Using tools such as Firebug, or Chrome's Web Inspector, or inspecting the
webserver access logs, confirm that the app is indeed making an
extraneous request to /app/%7B%7Bphone.imageUrl%7D%7D (or
/app/{{phone.imageUrl}}).
I did so and it gave me the correct result:
<li class="thumbnail ng-scope" ng-repeat="phone in phones">
<img src="img/phones/motorola-xoom.0.jpg">
</li>
Is there a reason why?
From Angular docs
The buggy way to write it:
<img src="http://www.gravatar.com/avatar/{{hash}}"/>
The correct way to write it:
<img ng-src="http://www.gravatar.com/avatar/{{hash}}"/>
Why? this is because on load of page, before angular bootstrapping and creation of controllers, browser will try to load image from http://www.gravatar.com/avatar/{{hash}} and it will fail. Then once angular is started, it understands that that {{hash}} has to be replaced with say logo.png, now src attribute changes to http://www.gravatar.com/avatar/logo.png and image correctly loads. Problem is that there are 2 requests going and first one failing.
TO solve this we should use ng-src which is an angular directive and angular will replace ng-src value into src attribute only after angular bootstrapping and controllers are fully loaded, and at that time {{hash}} would have already been replaced with correct scope value.
<img ng-src="{{phone.imageUrl}}">
This gives you expected result, because phone.imageUrl is evaluated and replaced by its value after angular is loaded.
<img src="{{phone.imageUrl}}">
But with this, the browser tries to load an image named {{phone.imageUrl}}, which results in a failed request.
You can check this in the console of your browser.
The src="{{phone.imageUrl}}" is unnecessary and creates an extra request by the browser. The browser will make at least 2 GET requests attempting to load that image:
before the expression is evaluated {{phone.imageUrl}}
after the expression is evaluated img/phones/motorola-xoom.0.jpg
You should always use ng-src directive when dealing with Angular expressions. <img ng-src="{{phone.imageUrl}}"> gives you the expected result of a single request.
On a side note, the same applies to ng-href so you don't get broken links till the first digest cycle kicks in.
Well actually it makes 100% sense because HTML gets processed sequentially and when this HTML page is being processed line by line, by the time it gets to this image, the line and processing the image, our phone.imageUrl is not yet defined yet.
And in fact, Angular JS has not yet processed this chunk of HTML, and hasn't yet looked for these placeholders and substitute these expressions with the values. So what ends up happening is that the browser gets this line and tries to fetch this image at this URL.
And of course this is a bogus URL, if it still has those mustache and curly braces in it, and therefore it gives you a 404, but once of course Angular takes care of this, it substitutes this URL for the proper one, and then we still see the image, but yet the 404 error message remains in our console.
So, how can we take care of this? Well, we can not take care of this using regular HTML tricks. But, we can take care of it using Angular. We need somehow to tell the browser not to try to fetch this URL but at the same time fetch it only when Angular is ready for interpretation of these placeholders.
Well, one way of doing it is to put an Angular attribute on here instead of the standard HTML one. And the Angular attribute is just ng-src. So if we say that now, go back, you'll see that there's no errors anymore because the image only got fetched once Angular got a hold of this HTML and translated all the expressions into their values.
I am going to create an application with Angularjs. I have several modals (with the ng-dialog libraries) to create, modify data like an user for example.
When I open it, I can always see during several milliseconds names variables with accolades like {{user.name}}, before it renders the real value.
It is not really beautiful and then if someone has an idea about how to manage this type of display problems, please share it.
Thank you in advance.
There are couple of ways to deal with it, you could either use ng-bind or ng-cloak directives
Check angular ngCloak directive documentation
https://docs.angularjs.org/api/ng/directive/ngCloak
You can use ng-bind. Here is the official documentation on it:
It is preferable to use ngBind instead of {{ expression }} if a template is momentarily displayed >by the browser in its raw state before Angular compiles it. Since ngBind is an element attribute, >it makes the bindings invisible to the user while the page is loading
Usage:
Hello <span ng-bind="name"></span>!
I have a few bits of HTML like
<p class="noresults">{{numberOfContacts}} Results Are Available</p>
Is it possible for me to hide {{numberOfContacts}} until Angular has loaded? So it would just say Results Are Available
I've seem some solutions such as hiding the entire body until Angular has loaded, but I'd rather not do that if possible.
Yes, use ng-cloak. Simply add class="ng-cloak" or ng-cloak to an element like this
Using directive <div ng-cloak></div>
Using class <div class="ng-cloak"></div>
It's simply a set of CSS rules with display: none !important and as Angular has rendered your DOM it removes the ng-cloak so an element is visible.
use <span ng-bind="numberOfContacts" /> instead of {{numberOfContacts}}
Sometimes, even if I used the ng-cloak, I could still see the braces for a few seconds. Adding the following style resolved my issue:
[ng-cloak]
{
display: none !important;
}
Please see this link link for more explanation.
Hope it helps :D
This is typically only an issue when working with complex content on really slow devices. In those instances, there can be a brief moment when the browser displays the HTML in the document while AngularJS is parsing the HTML, getting ready, and processing the directives. In this interval of time, any inline template expressions you have defined will be visible to the user. Most devices nowadays have pretty good browsers which are quick enough to prevent this from being an issue. There are two ways to solve the problem.
Avoid using inline template expressions and stick with ng-bind directive.
(Best) Use the ng-cloak directive which will hide the content until Angular has finished processing it. Basically, the ng-cloak directive uses CSS to hide the elements and angular removes the CSS class when the content has been processed, ensuring that the user never sees the {{ and }} characters of a template expression.
One strategy to consider is using the ng-cloak directly to the body element, which will ensure that the user will see an empty browser while AngularJS loads. However, you can be more specific by applying it to parts of the document where there are inline expressions.
I have seen issues with ng-cloak not working when added to an element. In the past, I have worked around this issue by simply adding ng-cloak class to element.
You can use ng-bind instead of expression like
<span ng-bind="data"></span>
Is there a way to prevent flicker for templates that contain concatenated values such as {{person.LastName+ ", " + person.FirstName}}?
I don't want to see the "," until $scope.person is bound.
Is this something that I might put into a filter? Would you create a filter for something this trivial?
You can use the ngCloak directive for that. From the docs:
The ngCloak directive is used to prevent the Angular html template
from being briefly displayed by the browser in its raw (uncompiled)
form while your application is loading. Use this directive to avoid
the undesirable flicker effect caused by the html template display.
You can simply use ng-show for this.
I've created a demo to show the results.
http://plnkr.co/edit/ZAC8RzagPYmLHgXcPazW?p=preview
I'm using a timeout of 2 seconds in the controller so you can see the flicker if you remove ng-show.
You can use "ng-bind" attribute in your wrapper tag so instead of this:
<span>{{person.LastName+ ", " + person.FirstName}}</span>
You can do this:
<span ng-bind="person.LastName + ', ' + person.FirstName"></span>
This will change the tag text only when the value is properly concatenated.
Had some issues with ng-cloak so i resorted to using plain old css:
<div class="digits" style="display:none;">
And on the controller:
document.querySelector('.digits').style.display = 'block';
This happens because you're loading your angular js lib not from the <head></head> section. If it's not a big deal to you, just move your angular <script> tag in the head and it should stop flickering.