Submit Button gets disabled after submit when errors are still there

Dear Tran,
I came across with the problem that was freezing the form when I submit the form. Detailed description about this is as follows.
1) I have filled up the form clicked submit button
2) Form has still errors so the cursor focused to first error field
3) cleared errors in the form by filling up valid data & tried to submit but button was disabled & there is no road to go ahead.
I figured out a solution to that is
a) Found that script in this plugin is disabling submit button for saving from multiple submits.
b) I have fixed this script using following modification of the script

setTimeout( function() {
                $this.children( '.rwmb-form-submit' ).children( 'button' ).prop( 'disabled', true );
            }, 0 ); 

changed to

setTimeout( function() {
                    if ($this.valid()) {
                        $this.children( '.rwmb-form-submit' ).children( 'button' ).prop( 'disabled', true );
                    }  else {
                        $this.children( '.rwmb-form-submit' ).children( 'button' ).prop( 'disabled', false);
                    }
 }, 0 ); 

Please guide me that the path is correct?
Regards,
Calpaq