Immediate Image preview in jasny bootstrap on ajax upload

Question

I am using Jasny Bootstrap to display file preview when it is selected.

      <div class="fileinput fileinput-new" data-provides="fileinput">
        <div>
         <span class="btn btn-primary btn-file"><span class="fileinput-new"><span class="fa fa-camera"></span> Image 3</span>
          <div class="fileinput-preview fileinput-exists thumbnail" style="max-width: 200px; max-height: 150px;"></div>
          <input type="file" name="file" class="ephoto-upload" accept="image/jpeg"></span>
          </div>
        </div>

I would like to start submission of this image via ajax as soon as image is selected. I am using following code.

<script>
$('.ephoto-upload').change(function(){
if($(this).val()!='') {   
var formData = new FormData();
formData.append('file', $(this)[0].files[0]);
$.ajax({
    url: '/path/to/upload',
    type: 'POST',
    data: formData,
    async: false,
    success: function (r) { 
    if(r.success) {
    //success work 
     }
    },
    cache: false,
    contentType: false,
    processData: false
});

}

}); 
</script>

Upload works fine but the preview of image is displayed after ajax upload is completed.So for sometime page get freezes and after that preview is displayed. But I want to display the preview as soon as image gets selected and after displaying the selected image, Ajax get execute.

Answer 1

You're setting your ajax async=false that means the navigator is gonna freez until the image has been uploaded.

In other hand this is what you wanted:

<form>
    <div class="fileinput fileinput-new" data-provides="fileinput">
        <div>
         <span class="btn btn-primary btn-file"><span class="fileinput-new"><span class="fa fa-camera"></span> Image 3</span>
          <div id="preview" name="preview"  class="fileinput-preview fileinput-exists thumbnail" style="width: 200px; height: 150px; display:block;"></div>
             <img id="prevImg" name="prevImg" />   
          <input type="file" name="file" id="file" class="ephoto-upload" accept="image/jpeg"></span>
          </div>
        </div>

</form>

js:

$('.ephoto-upload').change(function(){
    previewURL(this);
    if($(this).val()!='') {   
      var formData = new FormData();
      formData.append('file', $(this)[0].files[0]);
      $.ajax({
        url: '/path/to/upload',
        type: 'POST',
        data: formData,
        success: function (r) { 
        if(r.success) {
        //success work 
      }
    },
    cache: false,
    contentType: false,
    processData: false
});

}
}); 

function previewURL(input) {
        if (input.files && input.files[0]) {
            var reader = new FileReader();

            reader.onload = function (e) {
                //$('#prevImg').attr('src', e.target.result);
                $('#preview').css("background", "url(" + e.target.result +")" + " right top no-repeat");  
            }

            reader.readAsDataURL(input.files[0]);
        }
    }

I deleted the async=false because default is true.

Here's the demo