createTextNode without htmlentities

Consider the following snippet:

var t = "<span>Hello world</span>";
var range = window.getSelection().getRangeAt(0);
range.deleteContents();
range.insertNode(document.createTextNode(t));

How can I avoid replacing t with htmlentities?

By not creating a textnode. Instead use range.pasteHTML.

Don't use a textnode.

var t = document.createElement('span');
t.textContent = 'Hello world';
var range = window.getSelection().getRangeAt(0);
range.deleteContents();
range.insertNode(t);