JavaScript Promises

“I Promise a Result!”

“Producing code” is code that can take some time

“Consuming code” is code that must wait for the result

A Promise is an Object that links Producing code and Consuming code

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

https://www.geeksforgeeks.org/promise-vs-callback-in-javascript/

https://www.w3schools.com/js/js_promise.asp

JavaScript Callbacks

I will call back later!”

A callback is a function passed as an argument to another function

This technique allows a function to call another function

A callback function can run after another function has finished.

// The add() function is 
// called with arguments a, b
// and callback, callback 
// will be executed just
// after ending of add() function
function add(a, b, callback) {
    console.log(`The sum of ${a} 
    and ${b} is ${a + b}`);
    callback();
}
 
// The disp() function is called just
// after the ending of add() function
function disp() {
    console.log(`This must be printed
     after addition`);
}
 
// Calling add() function
add(5, 6, disp)

Reference

https://developer.mozilla.org/en-US/docs/Glossary/Callback_function

https://www.geeksforgeeks.org/promise-vs-callback-in-javascript/

https://www.w3schools.com/js/js_callback.asp

Creating multi-column Dropdown in ASP.NET Core

Generally, in Asp.net core, to display multiple columns in the select elements, we could write our own control or use some JQuery plugins.

Here are some examples;

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/option

https://dzone.com/articles/creating-a-multi-column-dropdown-in-aspnet-mvc

https://learn.microsoft.com/en-us/answers/questions/1251310/multi-column-drop-down-list-javascript-control-opt