How to Avoid Infinite Loops When Adding Directives from a Wrapper Directive in AngularJS?

Incorporating Multiple Directives from a Wrapper Directive

Overview

This question explores how to create a wrapper AngularJS directive that adds additional directives to the element it is applied to. The goal is to avoid an infinite loop when attempting to add and then compile the new directives using $compile.

Approach

The provided solution employs the following steps:

1. Priority and Terminal Settings:

   • Set the priority of the wrapper directive to a high value (e.g., 1000) using the priority property. This ensures that it runs before other directives on the same element.
   • Set the terminal property to true. This prevents AngularJS from compiling any other directives after the wrapper directive has run.

2. Directive Compilation:

   • In the compile function of the wrapper directive, add the desired directives to the element using element.attr(), and remove the wrapper directive's attribute to prevent an infinite loop.
   • $compile the element to incorporate the added directives.

Example

<code class="javascript">angular.module('app')
  .directive('commonThings', function ($compile) {
    return {
      restrict: 'A',
      replace: false,
      terminal: true,
      priority: 1000,
      link: function (scope, element, attrs) {
        element.attr('tooltip', '{{dt()}}');
        element.attr('tooltip-placement', 'bottom');
        element.removeAttr("common-things"); // Remove the wrapper directive's attribute
        element.removeAttr("data-common-things"); // Also remove the same attribute with data- prefix

        $compile(element)(scope);
      }
    };
  });</code>

Justification

• Setting terminal: true ensures that the wrapper directive is compiled first and that other directives are bypassed.
• Removing the wrapper directive's attribute prevents it from being re-compiled in subsequent $compile calls.
• By initially compiling the element without the wrapper directive's attributes, the subsequent $compile call takes care of compiling any skipped directives.

Conclusion

This approach provides a robust solution for incorporating multiple directives from a wrapper directive while avoiding the potential for infinite loops. The priority and terminal properties are crucial in achieving the desired behavior, and it is important to remove the wrapper directive's attribute after modifying the element to prevent further compilation.

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