Promise

Promises are meant to be asynchronous

New Promise takes two arguments, resolve and reject. Then executes the resolve callback,.catch executes reject, and.finally executes the result of a success or failure

Promise instance: if the image loads successfully, it will be displayed; if it fails, it will raise the image error

cosnt imgAdd = 'img'
const imgPromise  = (url) = > {
    return new Promise ((resolve,reject) = > {
        const img = new Image()
        img.src = url
        img.onload = () = > {
            resolve(img)
        }
        img.onerror = () = > {
            reject(new Error('Picture error'))
        }
    }) 
}

imgPromise(imgAdd)
    .then(img= > {
        docoument.body.appendChild(img)
    })
    .catch(err= > {
        document.body.innerHTML = err
    })
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