How to Dynamically Add Directives in AngularJS without an Infinite Loop?

Adding Directives Dynamically with AngularJS

When building complex UI elements in AngularJS, it may be necessary to dynamically add directives to a DOM element. One approach to achieve this is by creating a higher-order directive that manages the addition of multiple directives.

Implementation with Conditional Compilation

One method is to check if the desired directives have already been added before attempting to add them. This approach involves setting conditional checks within the directive's link function:

<code class="javascript">angular.module('app')
  .directive('superDirective', function ($compile, $injector) {
    return {
      restrict: 'A',
      replace: true,
      link: function (scope, element, attrs) {
        if (element.attr('datepicker')) { // Check for existing directive
          return;
        }
        element.attr('datepicker', 'someValue'); // Add directive attribute
        // Add other directive attributes
        $compile(element)(scope);
      }
    };
  });</code>

This approach, however, may result in an infinite loop if the added attributes are not correctly removed from the element.

Solution with Priority and Terminal Directives

To avoid infinite loop and ensure proper directive execution, a combination of the priority and terminal properties can be used:

<code class="javascript">angular.module('app')
  .directive('commonThings', function ($compile) {
    return {
      restrict: 'A',
      replace: false, 
      terminal: true, // Skips compilation of subsequent directives on this element
      priority: 1000, // Executes before other directives
      link: function (scope, element, attrs) {
        // Add tooltip and tooltip placement directives
        element.attr('tooltip', '{{dt()}}');
        element.attr('tooltip-placement', 'bottom');
        // Remove the directive attribute to prevent recursive compilation
        element.removeAttr("common-things"); 
        element.removeAttr("data-common-things");
        // Compile the element again, including the added directives
        $compile(element)(scope);
      }
    };
  });</code>

Setting terminal to true prevents the compilation of subsequent directives on the same element. A high priority ensures that the custom directive is compiled before others. Removing the directive attribute afterward prevents infinite looping. This approach ensures that the added directives are executed correctly without causing any interference.

The above is the detailed content of How to Dynamically Add Directives in AngularJS without an Infinite Loop?. For more information, please follow other related articles on the PHP Chinese website!