<!DOCTYPE html>
<meta charset="utf-8">
<html>
<style>
html, body {
    margin: 0;
    font-family: -apple-system;
}

#source, #destination {
    width: 100%;
    margin: 0;
}

#destination {
    height: 1024px;
}

#source {
    font-size: 150px;
    white-space: nowrap;
    height: 200px;
}
</style>
<body>
    <div id="source">Rich text</div>
    <div id="destination" contenteditable></div>
    <pre id="output"></pre>
</body>
<script>

function handleCopy1(event) {
    event.clipboardData.setData("Text", "");
    event.clipboardData.setData(" URL\r", "http://www.apple.com/");
    event.clipboardData.setData(" text/html;charset=utf-8 ", "<b style='color: green'></b>");
    event.clipboardData.setData("custom type\t\n", "custom data");
    event.preventDefault();
}

function handleCopy2(event) {
    event.clipboardData.setData("text/plain;\t", "");
    event.clipboardData.setData("text/uri-list;\n", "http://www.apple.com/");
    event.clipboardData.setData("text/html;    ", "<b style='color: green'></b>");
    event.clipboardData.setData("custom type", "custom data");
    event.preventDefault();
}

function getDataWithTypesFromEvent(event, types) {
    const result = {};
    for (const type of types)
        result[type] = event.clipboardData.getData(type);
    return result;
}

function handlePaste1(event) {
    output.textContent += JSON.stringify(getDataWithTypesFromEvent(event, [" text/plain; ", "text/uri-list; ", "text/html; ", "\fcustom type\r"]), null, "    ") + "\n";
    event.preventDefault();
}

function handlePaste2(event) {
    output.textContent += JSON.stringify(getDataWithTypesFromEvent(event, ["\tText", "\r\nURL", "    text/html;charset=utf-8 ", " custom type\t\n"]), null, "    ") + "\n";
    event.preventDefault();
}

getSelection().setBaseAndExtent(source, 0, source, 1);
source.addEventListener("copy", handleCopy1);
destination.addEventListener("paste", handlePaste1);

if (window.testRunner && window.internals) {
    internals.settings.setCustomPasteboardDataEnabled(true);
    testRunner.dumpAsText();
    testRunner.execCommand("Copy");
    destination.focus();
    testRunner.execCommand("Paste");
    destination.blur();

    source.removeEventListener("copy", handleCopy1);
    source.addEventListener("copy", handleCopy2);
    destination.removeEventListener("paste", handlePaste1);
    destination.addEventListener("paste", handlePaste2);

    getSelection().setBaseAndExtent(source, 0, source, 1);
    testRunner.execCommand("Copy");
    destination.focus();
    testRunner.execCommand("Paste");
}
</script>
</html>