I have seen aria-haspopup attribute being used on toolbar menu of applications such as WYSIWYG editor. However, I haven't seen it being used on the main navigation in any ARIA demonstration website.
Was this attribute introduced mainly for toolbar menu of applications? Is it appropriate and reasonable to use it on the main navigation (which has submenu) of a website?
Just saw this attribute being used on the markup of jQuery UI Selectmenu (on the a element, which is the switch of selectmenu). So it seems to be okay to use it on any code.
<span class="ui-selectmenu-button css-scope">
<a class="ui-corner-all ui-state-default ui-widget ui-button" href="#speed" tabindex="0" id="speed-button" role="combobox" aria-expanded="false" aria-autocomplete="list" aria-owns="speed-menu" aria-haspopup="true">
<span class="ui-icon-triangle-1-s ui-icon"></span>
<span class="ui-selectmenu-text">Medium</span>
</a>
</span>
来源：https://stackoverflow.com/questions/11169626/is-aria-haspopup-attribute-mainly-for-toolbar-menu