How to run a callback function on a jQuery trigger("click")?

When you call trigger, the bound event handler is immediately executed, so you don't need any callback. Just use

$input.trigger('click');
runtests();

Yes - It is true that trigger doesn't take callback but we can pass callback as parameter.

//.trigger( eventType [, extraParameters ] )

$("#element").bind("customCall", function(e, callback){
   callback();
}
var callback = function(){alert("Hello");}
$("#element").trigger("customCall",[callback]);

Hope this will helps

First you need to bind the click event and then you can trigger the click event.

$input.bind('click', function() {

     console.log("clicked the input");
});

$input.trigger('click');