callback3.js

firstFunctionCall : find([1,2], function(elements) {
    alert("Results : "+elements);
});

alert("meanwhile I show up");

function find(elements, callback) {
    //The time consuming operation
    setTimeout(function() {
        elements.push(3,4,5);
            if(typeof callback === "function") {
                callback(elements);
            }
            else {
                alert("Retrieved function is not a callback");
            }
                
    } ,2000);
}