let pngUrl; function convert() { const jpgFile = document.getElementById('jpg-file').files[0]; if (!jpgFile) { alert('Please select a JPG file'); return; } const reader = new FileReader(); reader.readAsDataURL(jpgFile); reader.onload = (event) => { const img = new Image(); img.src = event.target.result; img.onload = () => { const canvas = document.createElement('canvas'); canvas.width = img.width; canvas.height = img.height; const context = canvas.getContext('2d'); context.drawImage(img, 0, 0); canvas.toBlob((blob) => { pngUrl = URL.createObjectURL(blob); alert('Conversion successful'); }, 'image/png'); } } } function download() { if (!pngUrl) { alert('Please upload a JPG file and convert it to PNG first'); return; } const a = document.createElement('a'); a.href = pngUrl; a.download = 'converted.png'; a.click(); }