JSFiddle - React, Tailwind, and code Playground

JavaScript

function GetAllFileNames(ms) {
    //simulate delay
    setTimeout( function() { console.log('Get all files names') ; return 20;}, ms);
} 

function getfilenames() {

    var def = $.Deferred();
    
    def.resolve(GetAllFileNames(2000));

    return def;
}

getfilenames().then( function() { console.log('Got all file names'); });