in cloud-functions-start/public/scripts/main.js [163:173]
function onMessageFormSubmit(e) {
e.preventDefault();
// Check that the user entered a message and is signed in.
if (messageInputElement.value && checkSignedInWithMessage()) {
saveMessage(messageInputElement.value).then(function() {
// Clear message text field and re-enable the SEND button.
resetMaterialTextfield(messageInputElement);
toggleButton();
});
}
}