The foreground downloads network pictures without background processing

let url = 'https://s-cf-tw.shopeesz.com/file/5d5b0c9ff52be2ce2bd5aa47f9791cc1';
                             let image = new Image()
                             image.setAttribute('crossOrigin', 'anonymous')
                             image.src = url
                             image.onload = () => {
    
                                   let canvas = document.createElement('canvas')
                                   canvas.width = image.width
                                   canvas.height = image.height
                                   let ctx = canvas.getContext('2d')
                                   ctx.drawImage(image, 0, 0, image.width, image.height)
                                   canvas.toBlob((blob) => {
    
                                         let url = URL.createObjectURL(blob)
                                       let eleLink = document.createElement('a')
                                          eleLink.download = 'dsfad'
                                          eleLink.href = url
                                          eleLink.click()
                                          eleLink.remove()
                                         URL.revokeObjectURL(url)
                                       })
                                 }