AngularJS ng-disabled directive with expression is not working

Question

User Story: When a new user clicks the New User checkbox and accepts the TermsAndConditions radio button, the Register button should be enabled.

My code in angularJS

Answer 1

The ng-disabled expression is evaluated in the present scope. Hence, you should only need the following without any extra interpolation with {{..}}:

Note that I added a ! since you probably want the button disabled if the user has not accepted the TnC.

Working demo: http://plnkr.co/edit/95UiO4Rd2IMh8T1KjSQK?p=preview

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A comment was posted below asking how to reason about when to use {{...}} and when to use bare expression with a given ng-* directive. Unfortunately, there is no syntactical clue hidden in the directives which can reveal that information. Looking at the documentation will turn out to be fastest way to find out this information.