boards/static/js/form.js

$('input[name=image]').wrap($('<div class="file_wrap"></div>'));

$('body').on('change', 'input[name=image]', function(event) {
    var file = event.target.files[0];

    if(file.type.match('image.*')) {
        var fileReader = new FileReader();

        fileReader.addEventListener("load", function(event) {
            var wrapper = $('.file_wrap');

            wrapper.find('.file-thumb').remove();
            wrapper.append(
                $('<div class="file-thumb" style="background-image: url('+event.target.result+')"></div>')
            );
        });

        fileReader.readAsDataURL(file);
    }
});

var form = $('#form');
$('textarea').keypress(function(event) {
    if (event.which == 13 && event.ctrlKey) {
        form.submit();
    }
});

$('#preview-button').click(function() {
    var data = {
        raw_text: $('textarea').val()
    }

    var diffUrl = '/api/preview/';

    $.post(diffUrl,
        data,
        function(data) {
            var previewTextBlock = $('#preview-text');
            previewTextBlock.html(data);
            previewTextBlock.show();
        })
})