How do I access transclusion slots from the transclude function?

Question

Angular 1.5 introduced multi-slot transclusion. According to the docs:

the transclude object { slotA: '?myCustomElement' } maps elements to the slotA slot, which can be accessed via the $transclude function

Unfortunately it doesn't give any examples of this. The only example it gives doesn't mention slots at all:

$transclude(function(clone, scope) {
  element.append(clone);
  transcludedContent = clone;
  transclusionScope = scope;
});

Can someone shed some light on how to access each slot using the $transclude function?

Answer 1

I had similar problem, but reading source code of ng-transclude helps. It turns out there is third argument to $transclude function, which is slot name.

https://github.com/angular/angular.js/blob/master/src/ng/directive/ngTransclude.js#L190

Simple example:

angular.module('app', []);

angular
  .module('app')
  .directive('dir', function () {
    return {
      transclude: {
        a: 'aT',
        b: 'bT'
      },
      link: function (scope, elem, attrs, ctrl, transclude) {
        transclude(function (content) {
          elem.append('<div>a</div>');
          elem.append(content);
        }, null, 'a');
        
        transclude(function (content) {
          elem.append('<div>b</div>');
          elem.append(content);
        }, null, 'b');
      }
    };
  });

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.7/angular.js"></script>

<div ng-app="app">
  <dir>
    <a-t>content of a</a-t>
    <b-t>content of b</b-t>
  </dir>
</div>