[angularjs] What is the difference between ng-app and data-ng-app?


None in terms of the runtime behavior, those are just different styles of naming directives as described here: http://docs.angularjs.org/guide/directive

Directives have camel cased names such as ngBind. The directive can be invoked by translating the camel case name into snake case with these special characters :, -, or _. Optionally the directive can be prefixed with x-, or data- to make it HTML validator compliant. Here is a list of some of the possible directive names: ng:bind, ng-bind, ng_bind, x-ng-bind and data-ng-bind.

As you can see from reading this the data- can be used to make your HTML pass HTML validator tests/


I have begun to learn about AngularJS and am confused about what the differences are between the ng-app and data-ng-app directives.

The basic difference between these two terms is that data-ng-app validates the HTML while the latter don't.Functionality remains the same. For more reference you can try w3Validator.

In modern browsers there is no difference, but in older IEs, they won't work unless you declare an XML namespace defining it.

There is also a validation difference in that ng-app is not valid XHTML, and will cause your webpage to fail HTML validations. Angular allows you to prefix its directives with data- or x- to allow it to validate.