promises.js

const config = {}

document.addEventListener('load', ()=>{
    setUpPage()
})

function setUpPage(){
    return new Promise(function(resolve, reject){
        let update = config['dev'] = 100
        try{
        update = () => resolve()}
        catch{
            update = () => reject(new Error('Cannot find config!'))
        }
    })
}

promise = setUpPage()

promise.then(
    console.log(config['dev'])
)

function make_bacon(){
    console.log(config['dev'])
}