Core htmx API test

• onLoad is called... onLoad11ms ‣

  // also tests on/off
  this.server.respondWith('GET', '/test', "<div id='d1' hx-get='/test'></div>")
  var helper = htmx.onLoad(function(elt) {
    elt.setAttribute('foo', 'bar')
  })
  try {
    var div = make("<div id='d1' hx-get='/test' hx-swap='outerHTML'></div>")
    div.click()
    this.server.respond()
    byId('d1').getAttribute('foo').should.equal('bar')
    htmx.off('htmx:load', helper)
  } catch (error) {
    // Clean up the event if the test fails, then throw it again
    htmx.off('htmx:load', helper)
    throw error
  }