Jquery – How to load values into an HTML form with jQuery

Firefox 30 ignores autocomplete="off" for passwords, opting to prompt the user instead whether the password should be stored on the client. Note the following commentary from May 5, 2014:

• The password manager always prompts if it wants to save a password. Passwords are not saved without permission from the user.
• We are the third browser to implement this change, after IE and Chrome.

According to the Mozilla Developer Network documentation, the Boolean form element attribute autocomplete prevents form data from being cached in older browsers.

<input type="text" name="foo" autocomplete="off" />

With HTML5 you can make file uploads with Ajax and jQuery. Not only that, you can do file validations (name, size, and MIME type) or handle the progress event with the HTML5 progress tag (or a div). Recently I had to make a file uploader, but I didn't want to use Flash nor Iframes or plugins and after some research I came up with the solution.

The HTML:

<form enctype="multipart/form-data">
    <input name="file" type="file" />
    <input type="button" value="Upload" />
</form>
<progress></progress>

First, you can do some validation if you want. For example, in the .on('change') event of the file:

$(':file').on('change', function () {
  var file = this.files[0];

  if (file.size > 1024) {
    alert('max upload size is 1k');
  }

  // Also see .name, .type
});

Now the $.ajax() submit with the button's click:

$(':button').on('click', function () {
  $.ajax({
    // Your server script to process the upload
    url: 'upload.php',
    type: 'POST',

    // Form data
    data: new FormData($('form')[0]),

    // Tell jQuery not to process data or worry about content-type
    // You *must* include these options!
    cache: false,
    contentType: false,
    processData: false,

    // Custom XMLHttpRequest
    xhr: function () {
      var myXhr = $.ajaxSettings.xhr();
      if (myXhr.upload) {
        // For handling the progress of the upload
        myXhr.upload.addEventListener('progress', function (e) {
          if (e.lengthComputable) {
            $('progress').attr({
              value: e.loaded,
              max: e.total,
            });
          }
        }, false);
      }
      return myXhr;
    }
  });
});

As you can see, with HTML5 (and some research) file uploading not only becomes possible but super easy. Try it with Google Chrome as some of the HTML5 components of the examples aren't available in every browser.