What is the best way to conditionally apply a class?

Question

Lets say you have an array that is rendered in a ul with an li for each element and a property on the controller called selectedIndex.

Answer 1

You can use this npm package. It handles everything and has options for static and conditional classes based on a variable or a function.

// Support for string arguments
getClassNames('class1', 'class2');

// support for Object
getClassNames({class1: true, class2 : false});

// support for all type of data
getClassNames('class1', 'class2', ['class3', 'class4'], { 
    class5 : function() { return false; },
    class6 : function() { return true; }
});