How encode in base64 a file generated with jspdf and html2canvas?

问题

i'm trying encode the document generated in the attached code, but nothing happens, not generate error but neither encodes the file, and the ajax request is never executed

what is the correct way?

    html2canvas(document.getElementById("workAreaModel"), {
    onrendered: function(canvas)
    {
        var img = canvas.toDataURL("image/png");
        var doc = new jsPDF("l", "pt", "letter");
        doc.addImage(img, 'JPEG',20,20);
        var fileEncode = btoa(doc.output());
         $.ajax({
              url: '/model/send',
              data: fileEncode,
              dataType: 'text',
              processData: false,
              contentType: false,
              type: 'GET',
              success: function (response) {
                   alter('Exit to send request');
              },
              error: function (jqXHR) {
                  alter('Failure to send request');
              }
             });
    }
});

回答1:

First, jsPDF is not native in javascript, make sure you have included proper source, and after having a peek on other references, I think you don't need btoa() function to convert doc.output(), just specify like this :

 doc.output('datauri');

Second, base-64 encoded string is possible to contain ' + ' , ' / ' , ' = ', they are not URL safe characters , you need to replace them or you cannot deal with ajax .

However, in my own experience, depending on file's size, it's easy to be hell long ! before reaching the characters' length limit of GET method, encoded string will crash your web developer tool first, and debugging would be difficult.

My suggestion, according to your jquery code

processData: false,
contentType: false

It is common setting to send maybe File or Blob object, just have a look on jsPDF, it is availible to convert your data to blob :

doc.output('blob');

so revise your code completely :

var img = canvas.toDataURL("image/png");
var doc = new jsPDF("l", "pt", "letter");
doc.addImage(img, 'JPEG',20,20);
var file = doc.output('blob');
var fd = new FormData();     // To carry on your data  
fd.append('mypdf',file);

$.ajax({
   url: '/model/send',   //here is also a problem, depends on your 
   data: fd,           //backend language, it may looks like '/model/send.php'
   dataType: 'text',
   processData: false,
   contentType: false,
   type: 'POST',
   success: function (response) {
     alter('Exit to send request');
   },
   error: function (jqXHR) {
     alter('Failure to send request');
   }
});

and if you are using php on your backend , you could have a look on your data information:

echo $_FILES['mypdf'];

来源：https://stackoverflow.com/questions/38559604/how-encode-in-base64-a-file-generated-with-jspdf-and-html2canvas

标签

javascript

jspdf

html2canvas