How can I execute a JavaScript function before the form submission handler is called?
Remove #submit.

$form['submit'] = array(
  '#type' =&gt; 'submit',
  '#value' =&gt; 'Save',
  '#attributes' =&gt; array(
    'id' =&gt; 'myid_save',               
  ),
);


Your submit function should be myid_user_page_form_submit rather than formsave_action. If your form's function name is myform_form, then you just need to write the submit handler like myform_form_submit. It will consider it automatically.

Now change your js to :

$('#myid_save').on('click', function(e) {               
    myid_save_signature();  
    myid_save_photo();
    $('#myid_save').submit(); // Add this line                 
});


It will submit your form using jquery.