split-page.js

(() => {
	let e = document.createElement('button');
	e.innerText = 'split';
    e.style = `
        position: absolute;
        right: 0px;
        bottom: 0px;
        z-index: 1;
        border: 1px solid #000000;
    `;
	e.onclick = () => {
		document.documentElement.innerHTML = `\
<frameset cols="50,50">
   <frame src="${document.location.href}">
   <frame src="${document.location.href}">
</frameset>`;
	}
	document.body.appendChild(e);
})();