AngularJS directive - setting order for multiple d

问题:

Considering this markup with a directive "foo":

<div foo run="3"></div>
<div foo run="1"></div>
<div foo run="2"></div>

What is a good approach for causing "foo" to run in the specified order rather than from top to bottom (3,1,2)? The only thing I can think to do would be tracking what has run and returning false on the items that are not in order, then making angular try to run them all again and repeat until they are all done. That sounds terrible to me though, because it would have to repeat so many times... Does Angular have something built-in that can be used? Is there an ideal approach for dealing with this?

回答1:

OK, here's my solution, although it's more a template.

Fiddle (check the console log to see the result)

I've wrapped the foo directive in a fooParent directive, like so:

<div foo-parent>
    <div foo run="3"></div>
    <div foo run="1"></div>
    <div foo run="2"></div>
</div>

The fooParent directive exists pretty much to do three things:

1. Expose a function to foo items so they can be added to a general list
2. Maintain a list of foos, which will be sorted during post-linking
3. Process each foo in the run order specified.

It looks like this:

app.directive('fooParent', function() {
    var foos = [];
    return {
        restrict: 'A',
        controller: ['$scope', '$element', '$attrs', '$transclude', function($scope, $element, $attrs, $transclude) {
            this.addFoo = function(runOrder, element) {
                foos.push({
                    run: 1*runOrder, // make sure run is an integer
                    element: element
                });
            };
        }],
        link: function(scope, element, attrs) {
            foos.sort(function(a, b) {
                return a.run - b.run;
            });
            // process all children here
            angular.forEach(foos, function(foo) {
                console.log(foo);
            });
        }
    };
});

And foo simply looks like:

app.directive('foo', function() {
    return {
        restrict: 'A',
        require: '^fooParent',
        link: function(scope, element, attrs, fooParent) {
            fooParent.addFoo(attrs.run, element);
        }
    };
});

Obviously, you will have to figure out the best way to handle remotely loading your content, especially if you want it to be serially loaded. Your foo directive would become much more simplified, since the loading and processing would have to occur within fooParent.

回答2:

Credit to OverZealous for inspiring my answer. Test it here. http://jsbin.com/apumaj/21/edit

the html (directive output will be displayed in this order, of course)

<div foo run="7"></div>
<div foo run="3"></div>
<div foo run="1"></div>
<div foo run="2"></div>

and the directive (to make the directive output load in "run" order) should be self-explanatory

app.directive('foo', function() {
  var foos = [];
  var foosLength = document.querySelectorAll('[foo]').length;
    return {
        restrict: 'A',
        link: function(scope, element, attrs) {
          foos.push({element:element, run:attrs.run});
          if (foos.length === foosLength) {
             foos.sort(function(a, b) {
                return a.run - b.run;
            });
            console.log('ran in this order:');
            for (var i=0; i<foosLength; ++i) {
              //process foos!
              var foo = foos[i];
              console.log(foo.run);
              foo.element.text(foo.run);
            }
          }
        }
    };
});