Question: If priority is critical, Impact can be high & medium. For another priority impact will be High, Medium & Low

Object: Client Script – OnChange

Class: GlideForm

Script:

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
    if (isLoading || newValue === '') {
        var pr = g_form.getValue('priority');
        if (pr == 1) {
            g_form.removeOption('impact', 3);
        }
        return;
    }

    //Type appropriate comment here, and begin script below
    if (newValue == 1) {
        g_form.removeOption('impact', 3);
    } else {
        g_form.addOption('impact', 3, '3 - Low');
    }

}