function fileValidation() {

            var fileInput =

                document.getElementById('file');

            var filePath = fileInput.value;

            // Allowing file type

            var allowedExtensions =

                    /(\.jpg|\.jpeg|\.png|\.gif)$/i;

            if (!allowedExtensions.exec(filePath)) {

                alert('Invalid file type');

                fileInput.value = '';

                return false;

            }

            else

            {

                // Image preview

                if (fileInput.files && fileInput.files[0]) {

                    var reader = new FileReader();

                    reader.onload = function(e) {

                        document.getElementById(

                            'imagePreview').innerHTML =

                            '<img src="' + e.target.result

                            + '"/>';

                    };

                    reader.readAsDataURL(fileInput.files[0]);

                }

            }

        }