Comment tags are counted as part of the "exactly one root element" for templates for directives with replace mode

[alexturpin]

Templates for directives with replace mode to true can only have one root element, otherwise this error occurs. However, comment tags are also counted in that check. So for example, the following:

app.directive("superman", function() {
  return {
    restrict: "E",
    template: "<!-- Superman directive --><div>Here I am to save the day</div>",
    replace: true
  }
})

http://codepen.io/anon/pen/bazyI

Causes an error. Maybe this will be considered a won't-fix but our designer guide couldn't comprehend why the template suddenly stopped working when he added a comment. Perhaps comment tags should be ignored from that count.

[caitp]

yeah, maybe we should filter out comment nodes or something before asserting that there is only one element... hmm.

I guess I'll write a patch, but I'm not sure I expect it to land, because it could hurt performance a tiny bit

[alexturpin]

@caitp This is what I've implemented for ourself for reference

https://github.com/alexturpin/angular.js/commit/3d37efa42bff35fedcc8d259f1c80e5f963607e8

[caitp]

thanks, I've written an alternative version which will explicitly only remove comment nodes.

[g00fy-]

@caitp what if the ignored comment is a directive ?

[caitp]

See the PR --- Lucas already pointed this out, and it has been updated to only remove comment nodes if there is more than a single node.

In practice, nobody really uses comment directives, so I don't expect this to actually affect anyone regardless

[Narretz]

There's a note in the error message for this which specifically explains how this can happen with comments in templates. Might wanna if somebody tried to do this before and ran into some wontfix behavior (I wouldn't know why, just a head's up)

[caitp]

There was #8616 (no resolution),I don't really see anything else