How to Export HTML to PDF (multiple pages) using jQuery?

问题

I want to Export HTML to PDF using jQuery that is working fine but only for when HTML will finish in single page PDF.

But I'm facing difficultly export html to PDF when there is lots of data in html and PDF pages may be more than one.

My code:

   $("body").on("click", "#downloadPDF", function () {
        html2canvas($('#downloadPDFData')[0], {
            onrendered: function (canvas) {
                var data = canvas.toDataURL();
                var docDefinition = {
                    content: [{
                        image: data,
                        width: 500
                    }]
                };
                pdfMake.createPdf(docDefinition).download("report.pdf");
            }
        });
    });

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.22/pdfmake.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/0.4.1/html2canvas.min.js"></script>
    
  <button id="downloadPDF">Download PDF</button>
  
    <div id="downloadPDFData">
    <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
       <p>
   Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </p>
    </div>

What is wrong with my code

Answer will be appreciated!

回答1:

I found 2 issues...

1. Better use the latest version of pdfMake. You were using 0.1.22... I used 0.1.68 found on cdnjs.
1. Seems like pdfMake isn't able to "split" an image and spead to several pages... So you have to provide some already splitted chunks. Fortunately, I found a SO answer about this specifically... Which I very slightly adapted here.

You can choose a predefined page format, like letter or A4, etc as a pdfMake param. See possible options.

Then you will have to adjust the height of the splitted image chunks by try/fail. Here, I found that 775px seemed good for a letter page... But only tried it with the HTML you provided.

SO snippets are disallowing downloads. So, useless to make it a snippet but you can check my CodePen.

Some documentation:

html2canvas
pdfMake

// Slightly adapted function from this SO answer: https://stackoverflow.com/a/21937796/2159528
// It now returns the objects formatted for pdfMake
function getClippedRegion(image, x, y, width, height) {
  var canvas = document.createElement("canvas"),
      ctx = canvas.getContext("2d");

  canvas.width = width;
  canvas.height = height;

  //                   source region         dest. region
  ctx.drawImage(image, x, y, width, height, 0, 0, width, height);

  return {
    // Those are some pdfMake params
    image: canvas.toDataURL(),
    width: 500
  };
}

$("body").on("click", "#downloadPDF", function () {

  html2canvas($("#downloadPDFData")[0], {
    onrendered: function (canvas) {

      // split the canvas produced by html2canvas into several, based on desired PDF page height
      let splitAt = 775; // A page height which fits for "LETTER" pageSize...

      let images = [];
      let y = 0;
      while (canvas.height > y) {
        images.push(getClippedRegion(canvas, 0, y, canvas.width, splitAt));
        y += splitAt;
      }

      // PDF creation using pdfMake
      var docDefinition = {
        content: images,
        pageSize: "LETTER"
      };
      pdfMake.createPdf(docDefinition).download("report.pdf");
    }
  });
});

来源：https://stackoverflow.com/questions/65308280/how-to-export-html-to-pdf-multiple-pages-using-jquery

标签

javascript

html

jquery

pdf

pdf-generation