<!DOCTYPE html>
<html>
<body>
<div id="editor" contenteditable></div>
<script>
const editor = document.getElementById('editor');
editor.focus();

var clipboardData = {};
editor.addEventListener('paste', (event) => {
    clipboardData.types = Array.from(event.clipboardData.types);
    clipboardData.items = Array.from(event.clipboardData.items).map((item) => ({kind: item.kind, type: item.type}));
    clipboardData.values = clipboardData.types.map((type) => event.clipboardData.getData(type));
    clipboardData.files = Array.from(event.clipboardData.files);

    setTimeout(() => {
       let img = document.querySelector('img');
       if (img.complete)
           notifyLoaded();
       else
           img.onload = notifyLoaded;
    }, 0);
});

function notifyLoaded()
{
    if (window.webkit)
        webkit.messageHandlers.testHandler.postMessage('loaded');
    else
        alert('loaded');
}

</script>
</body>
</html>