The answer you’re looking for would be ‘mx.data.action’. You can specify how you want the Microflow to run there, pass it an object, and several other things. Mendix adds ‘mx’ to the browser environment, so you can call it directly. You don’t have to do ‘window.mx...’, for instance.
Take a look at the params option for this call, it lets you pass in GUIDs for objects, or an XPath for objects to apply the microflow to.
Hope this helps.