写这个的原因就是打电子发票不方便，这个代码是纯js不需要后端服务直接将两张电子发票的pdf转为两张图片渲染到一张A4纸上面（完全不浪费，发票也不会变大），自动完成打印分页，点击打印即可。亲测可用所有电子发票。
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<html><head><meta charset="utf-8" /><title>PDF文件转图片</title><script type="text/javascript" src="js/jquery-3.6.4.min.js"></script><script type="text/javascript" src="js/2.2.228pdf.min.js"></script><script type="text/javascript" src="js/2.2.228.pdf.worker.min.js"></script><script type="text/javascript" src="js/jszip.js"></script><script type="text/javascript" src="js/FileSaver.js"></script><style type="text/css">button {width: 120px;height: 30px;background: none;border: 1px solid #b1afaf;border-radius: 5px;font-size: 12px;font-weight: 1000;color: #384240;cursor: pointer;outline: none;margin: 0 0.5%}button:hover {background: #ccc;}#container {width: 65%;height: 75%;margin-top: 1%;border-radius: 2px;}.pdfInfos {margin: 0 2%;}</style></head><body><div class="showdata" style="margin-top:1%"><button id="pdf_tourl">合并多个pdf为一个</button><button id="prevpage">上一页</button><button id="nextpage">下一页</button><button id="exportImg">导出每一张图片</button><button onclick="wind_print()">打印</button><button onclick="choosePdf()">选择多个pdf文件</button><input style="display:none" id='chooseFile' type='file' accept="application/pdf" multiple="multiple"></div><div class="showdata" style="margin-top:1%"><span class="pdfInfos">页码：<span id="currentPages"></span><span id="totalPages"></span></span><span class="pdfInfos">文件名：<span id="fileName"></span></span><span class="pdfInfos">文件大小：<span id="fileSize"></span></span></div><div style="position: relative;"><div id="container"></div><img id="imgloading" style="position: absolute;top: 20%;left: 2%;display:none" src="loading.gif"></div></body><script>$("#pdf_tourl").click(function(){alert("可以使用PDF Arranger软件");});function wind_print(){$(".showdata").hide();$("#container").css("width","100%");$("#container").css("height","100%");window.print();$(".showdata").show();$("#container").css("width","65%");$("#container").css("height","75%");}var currentPages, totalPages var scale = 2; $('#chooseFile').change(function() {var pdfFilePath = $('#chooseFile').val();if (pdfFilePath) {$("#container").empty(); currentPages = 1; totalPages = 0; debuggervar filesdata = $('#chooseFile')[0].files; var fileSize=0;for (let i = 0; i < filesdata.length; i++) {fileSize += filesdata[i].size;}var mb;if (fileSize) {mb = fileSize / 1048576;if (mb > 10) {alert("文件大小不能>10M");return;}}if (filesdata.length === 1) {$("#fileName").text(filesdata[0].name);} else {$("#fileName").text(filesdata[0].name + "等 " + filesdata.length + " 个文件");}$("#fileSize").text(mb.toFixed(2) + "Mb");for (let j = 0; j < filesdata.length; j++) {var reader = new FileReader();reader.readAsDataURL(filesdata[j]);reader.onload = function(e) { pdfjsLib.getDocument(this.result).then(function(pdf) { if (pdf) {totalPages = pdf.numPages; $("#currentPages").text("1/");$("#totalPages").text(totalPages);for (var i = 1; i <= totalPages; i++) {var canvas = document.createElement('canvas');var cid=j+i;canvas.id = "pageNum" + cid;$("#container").append(canvas);var context = canvas.getContext('2d');renderImg(pdf, i, context);}}});};}}});function renderImg(pdfFile, pageNumber, canvasContext) {pdfFile.getPage(pageNumber).then(function(page) { var viewport = page.getViewport(scale); var newcanvas = canvasContext.canvas;newcanvas.width = viewport.width;newcanvas.height = viewport.height;newcanvas.style.width = "100%";newcanvas.style.height = "100%";if (pageNumber != 1) {newcanvas.style.display = "none";}var renderContext = {canvasContext: canvasContext,viewport: viewport};page.render(renderContext); });return;};$("#prevpage").click(function() {if (!currentPages || currentPages <= 1) {return;}nowpage = currentPages;currentPages--;$("#currentPages").text(currentPages + "/");var prevcanvas = document.getElementById("pageNum" + currentPages);var currentcanvas = document.getElementById("pageNum" + nowpage);currentcanvas.style.display = "none";prevcanvas.style.display = "block";})$("#nextpage").click(function() {if (!currentPages || currentPages >= totalPages) {return;}nowpage = currentPages;currentPages++;$("#currentPages").text(currentPages + "/");var nextcanvas = document.getElementById("pageNum" + currentPages);var currentcanvas = document.getElementById("pageNum" + nowpage);currentcanvas.style.display = "none";nextcanvas.style.display = "block";})$("#exportImg").click(function() {if (!$('#chooseFile').val()) {alert('请先上传pdf文件')return false;}var zip = new JSZip(); var images = zip.folder("images"); $("canvas").each(function(index, ele) {var canvas = document.getElementById("pageNum" + (index + 1));images.file("photo-" + (index + 1) + ".png", splitBase64(canvas.toDataURL("image/png", 1.0)), {base64: true});})zip.generateAsync({type: "blob"}).then(function(content) {saveAs(content, "imgFiles.zip"); });});function splitBase64(dataurl) {var arr = dataurl.split(',')return arr[1]}function choosePdf() {$("#chooseFile").click()}</script>
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