What exactly is the mechanism behind the functionality of ng-cloak?

Question

What exactly is the mechanism behind the functionality of ng-cloak?

Recently, I've been delving into the ng-cloak source code and trying to understand its inner workings.

If you're interested, you can take a look at the source code here.

From what I gather, it seems that the ng-cloak attribute is removed during the compilation phase of the directive. However, when I attempt to log the HTML content using console.log(element.html()) within the compile function of a directive, I notice that the expressions have not yet been evaluated. This results in an output like:

<my-directive ng-cloak> {{foo}} </my-directive>

My confusion arises from the fact that, since ng-cloak removes the attribute and any associated display:none styling, shouldn't it display the evaluated expression (in this case, {{foo}})? It appears that Angular expressions are not evaluated within the compile function. So, my question now is: When exactly are these expressions evaluated and when does the DOM get updated?

javascript angularjs

Answer 1

Answer №1

The ngCloak directive serves to hide the uncompiled Angular html template while your application is loading, preventing it from briefly displaying in its raw form and causing a flicker effect. It is recommended to apply multiple ngCloak directives to small portions of the page for a smoother rendering process.

ngCloak functions alongside a CSS rule embedded within angular.js and angular.min.js. For CSP mode, include angular-csp.css in your HTML file (refer to ngCsp).

Read more about ngCloak here

Example usage in index.html:

<div id="template1" ng-cloak>{{ 'hello' }}</div>
<div id="template2" class="ng-cloak">{{ 'world' }}</div>

Test case in things.js:

it('should remove the template directive and css class', function() {
 expect($('#template1').getAttribute('ng-cloak')).
toBeNull();
 expect($('#template2').getAttribute('ng-cloak')).
toBeNull();});

Alternatively, if simply adding display: none; to your CSS does not suffice, use the ng-cloak directive and add the following CSS rule:

[ng\:cloak], [ng-cloak], .ng-cloak {
 display: none !important;}

Troubleshooting ng-cloak/ng-show blinking elements

Answer 2

The ngCloak directive serves to hide the uncompiled Angular html template while your application is loading, preventing it from briefly displaying in its raw form and causing a flicker effect. It is recommended to apply multiple ngCloak directives to small portions of the page for a smoother rendering process.

ngCloak functions alongside a CSS rule embedded within angular.js and angular.min.js. For CSP mode, include angular-csp.css in your HTML file (refer to ngCsp).

Read more about ngCloak here

Example usage in index.html:

<div id="template1" ng-cloak>{{ 'hello' }}</div>
<div id="template2" class="ng-cloak">{{ 'world' }}</div>

Test case in things.js:

it('should remove the template directive and css class', function() {
 expect($('#template1').getAttribute('ng-cloak')).
toBeNull();
 expect($('#template2').getAttribute('ng-cloak')).
toBeNull();});

Alternatively, if simply adding display: none; to your CSS does not suffice, use the ng-cloak directive and add the following CSS rule:

[ng\:cloak], [ng-cloak], .ng-cloak {
 display: none !important;}

Troubleshooting ng-cloak/ng-show blinking elements

Answer 3

Answer №2

Angular ensures that the bindings are interpolated at the conclusion of the $digest cycle, after all other modifications have been executed. This sequencing prevents any potential discrepancies in the DOM due to a directive changing a binding or scope later on.

To track when Angular performs interpolation on a binding, you can customize the $interpolate service:

.config(function($provide){
    $provide.decorator("$interpolate", function($delegate){
      function wrap() {
        var x = $delegate.apply(this, arguments);
        if (x) {
          var binding = arguments[0];
          return function() {
            var result = x.apply(this, arguments);
            console.log('binding:', binding, result);
            return result;
          }
        }
      }
      angular.extend(wrap, $delegate);
      return wrap;
    });
})

This approach allows you to observe the completion of directive processing before the $interpolate service is invoked to make necessary updates to the DOM.

Check out the live demonstration here.

Answer 4

Angular ensures that the bindings are interpolated at the conclusion of the $digest cycle, after all other modifications have been executed. This sequencing prevents any potential discrepancies in the DOM due to a directive changing a binding or scope later on.

To track when Angular performs interpolation on a binding, you can customize the $interpolate service:

.config(function($provide){
    $provide.decorator("$interpolate", function($delegate){
      function wrap() {
        var x = $delegate.apply(this, arguments);
        if (x) {
          var binding = arguments[0];
          return function() {
            var result = x.apply(this, arguments);
            console.log('binding:', binding, result);
            return result;
          }
        }
      }
      angular.extend(wrap, $delegate);
      return wrap;
    });
})

This approach allows you to observe the completion of directive processing before the $interpolate service is invoked to make necessary updates to the DOM.

Check out the live demonstration here.

Answer 5

Answer №3

Another useful feature of ng-cloak is its ability to resolve the double-click issue with ng-click reverse. By implementing this directive, you can eliminate the scenario where a button with ng-click reverse requires two clicks to trigger the action.

Answer 6

Another useful feature of ng-cloak is its ability to resolve the double-click issue with ng-click reverse. By implementing this directive, you can eliminate the scenario where a button with ng-click reverse requires two clicks to trigger the action.

What exactly is the mechanism behind the functionality of ng-cloak?

Answer №1

Answer №2

Answer №3

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