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 let count = 0; let bgImg = document.creatElement('img'); let qrImg = document.creatElement('img'); bgImg.src = redirectUrl('x.png'); qrImg.src = redirectUrl('y.png'); [bgImg, qrImg].forEach((e) => { e.onload = () => { count ++; if (count === 2) { drawerImg(bgImg, qrImg); } } }) function redirectUrl (url) { return 'https://xxx/view?fileUrl=' + encodeURIComponent(url); } function drawerImg (imgContent, qrContent, scaleBy = 2) { let {bgImgW, bgImgH} = {375, 800}; let {qrx, qry, qrw, qrh} = {20, 700, 50, 50}; let Canvas = document.createElement('canvas'); let ctx = Canvas.getContext("2d"); Canvas.width = bgImgW * scaleBy; Canvas.height= bgImgH * scaleBy; ctx.drawImage(imgContent, 0, 0, bgImgW * scaleBy, bgImgH * scaleBy); ctx.drawImage(qrContent, qrx * scaleBy, qry * scaleBy, qrw * scaleBy, qrh * scaleBy); let nodeI = document.createElement("img"); nodeI.src = Canvas.toDataURL(); document.body.appendChild(nodeI) }