feat(tagsInput): Add track-by-expr option

[zhouzi]

I've added a track-by-expr option that allows using a custom expression for tracking tags. This way you can do whatever you want to handle the ng-repeat's track by.

I've also made a few changes to the canAdd and track functions so they are more consistent. Until now, canAdd would consider foo and Foo to be the same value while the track by wouldn't. It was also possible to introduce duplicate values with invalid text such as null and undefined.

[manar-mk]

How can I download this?

[zhouzi]

Since this PR is not merged yet, you can get the code from the wizbii/ngTagsInput repository. It then depends on how you are tracking your dependencies but you can also npm install wizbii/ngTagsInput --save. Note that the repository doesn't contain the generated files so you'll have to build it yourself. To do so, you'll need to:

1. Get the code
2. cd ngTagsInput
3. npm install grunt-cli -g
4. npm install
5. grunt pack:js

You will end up with a "build" folder that contains the javascript files. Let me know if you're having trouble going through this process and I'll see if I can get you a link to the minified version.

[manar-mk]

thanks for such a fast reply. Could you please give me the link for minified version. Cause of the Windows OS I've faced some permission errors with the last step

[zhouzi]

Here you go: jsfiddle.net/exbvfs7g (grab the code from the javascript panel). You can give it a try in this example by adding "design".

[manar-mk]

Thank you Gabin. It helped me a lot)

[ddolcimascolo]

:+1: We definitely need this. @mbenford any chance you can merge this PR ?