Convert blob to base64 | 易学教程

问题

This is a snippet for the code that I want to do Blob to Base64 string:

This commented part works and that when the URL generated by this is set to img src it displays the image:

var blob = items[i].getAsFile();
//var URLObj = window.URL || window.webkitURL;
//var source = URLObj.createObjectURL(blob);
//console.log(\"image source=\" + source);

var reader = new FileReader();
reader.onload = function(event){
console.log(event.target.result)
}; // data url!
var source = reader.readAsBinaryString(blob);

The problem is with the the lower code, the source variable generated is null

Update:

Is there an easier way to do this with JQuery to be able to create Base64 String from Blob file as in the code above?

回答1:

 var reader = new FileReader();
 reader.readAsDataURL(blob); 
 reader.onloadend = function() {
     var base64data = reader.result;                
     console.log(base64data);
 }

Form the docs readAsDataURL encodes to base64

回答2:

this worked for me:

var blobToBase64 = function(blob, callback) {
    var reader = new FileReader();
    reader.onload = function() {
        var dataUrl = reader.result;
        var base64 = dataUrl.split(',')[1];
        callback(base64);
    };
    reader.readAsDataURL(blob);
};

回答3:

you can fix problem by:

var canvas = $('#canvas'); 
var b64Text = canvas.toDataURL();
b64Text = b64Text.replace('data&colon;image/png;base64,','');
var base64Data = b64Text;

I hope this help you

回答4:

So the problem is that you want to upload a base 64 image and you have a blob url. Now the answer that will work on all html 5 browsers is: Do:

  var fileInput = document.getElementById('myFileInputTag');
  var preview = document.getElementById('myImgTag');

  fileInput.addEventListener('change', function (e) {
      var url = URL.createObjectURL(e.target.files[0]);
      preview.setAttribute('src', url);
  });
function Upload()
{
     // preview can be image object or image element
     var myCanvas = document.getElementById('MyCanvas');
     var ctx = myCanvas.getContext('2d');
     ctx.drawImage(preview, 0,0);
     var base64Str = myCanvas.toDataURL();
     $.ajax({
         url: '/PathToServer',
         method: 'POST',
         data: {
             imageString: base64Str
         },
     success: function(data) { if(data && data.Success) {}},
     error: function(a,b,c){alert(c);}
     });
 }

回答5:

var audioURL = window.URL.createObjectURL(blob);
audio.src = audioURL;

var reader = new window.FileReader();
reader.readAsDataURL(blob);
reader.onloadend = function () {
     base64data = reader.result;
     console.log(base64data);
}

回答6:

(async () => console.log(btoa(await new Response(blob).text())))();

new Response(blob).text().then(t => console.log(btoa(t)))

see Response's constructor, you can turn [blob, buffer source form data, readable stream, etc.] into Response, which can then be turned into [json, text, array buffer, blob] which async method/callbacks.

回答7:

Most easiest way in a single line of code

var base64Image = new Buffer( blob, 'binary' ).toString('base64');

来源：https://stackoverflow.com/questions/18650168/convert-blob-to-base64

标签

javascript

jquery