domReady!: a useful RequireJS plugin to ensure the DOM is loaded before your Magento 2 JavaScript execution

[dmitry_fedyuk (Dmitrii Fediuk)]

The official documentation: http://requirejs.org/docs/api.html#pageload
A usage example from the core:
https://github.com/magento/magento2/blob/43e3fd79/app/code/Magento/AdminNotification/view/adminhtml/web/toolbar_entry.js#L8

[dmitry_fedyuk (Dmitrii Fediuk)]

See also:

• How to insert some JavaScript to a *.phtml template in the proper way (x-magento-init)
• How to load a JavaScript on demand using RequireJS