JSFiddle - React, Tailwind, and code Playground

HTML

<div ng-app>
    <div ng-controller="yesNoController">
        <div ng-if="yes">Yes is defined, will display</div>
        <div ng-if="no">No is defined, but will not display on Angular 1.2.1</div>
        <div ng-if="!!no">No is defined, but we need to add a double bang for it to parse correctly</div>
        <div ng-if="notDefined">Not defined, will not display</div>
    </div>
</div>

JavaScript

function yesNoController($scope) {
    $scope.yes = "yes";
    $scope.no = "no";
    $scope.notDefined = undefined;
}