Power BI Embedded now has the capability to set a basic filter as a single selection filter. To do this, when editing the report, select the checkbox that says Require single selection at the bottom of the filter card.

It's now possible to have the same single selection filter behavior when using the JavaScript client APIs. Just add the "requireSingleSelection" parameter to your filter’s definition and set it to true.
var filter = {
…
requireSingleSelection: true
};

Learn more about Power BI Embedded Filters APIs.