minify JavaScript onload

[mems]

DOM 0 event listeners provide scopes that bound to the element:

scope [...]

5. If element is not null, then set scope to NewObjectEnvironment(element, true, scope).

— https://html.spec.whatwg.org/multipage/webappapis.html#internal-raw-uncompiled-handler

That means you can use:

<img src="about:error" onerror="console.log(this,onerror,body,src)">

Will log:

1. HTMLImageElement instance
2. image DOM 0 event listener
3. document.body
4. image src property value