Rather than inserting textnodes, you can use the .textContent property to directly set the text:

function init(evt) {
var time = new Date();
var locale = “en-gb”;
var date = time.getDate();
document.getElementById(“day”).textContent = date;

var weekday = time.toLocaleString(locale, { weekday: “long” });
document.getElementById(“weekday”).textContent = weekday;

var month = time.toLocaleString(locale, {month: “short”});
document.getElementById(“month”).textContent = month.toUpperCase();
}