`defer` has problems: http://stackoverflow.com/a/40535440/247696 http://stackoverflow.com/a/40535440/247696 There is no obvious easy way to wait for an `async`

`defer` has problems: http://stackoverflow.com/a/40535440/247696 http://stackoverflow.com/a/40535440/247696 There is no obvious easy way to wait for an `async` script to finish loading and executing before running code that depends on it. For instance, how would I load the jQuery library asynchronously before running code that depends on jQuery?