victorwesterlund.com/public/assets/js/modules/Glitch.mjs

import { default as Background } from "./Background.mjs";

export default class Glitch extends Background {
	constructor(target) {
		super(target);

		this.interval = {
			_this: this,
			_interval: null,
			// Queue the next glitch
			set next (timeout) {
				clearTimeout(this._interval);
				this._interval = setTimeout(() => this._this.glitch(), timeout);
			}
		}

		this.interval.next = 500;
		this.randBg();
	}

	// Generate random string of length from charset
	randStr(length = 2) {
		const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
		let output = "";
		for(let i = 0; i < length; i++) {
			output += charset.charAt(Math.floor(Math.random() * charset.length));
		}
		return output;
	}

	// Create a glitchy image
	glitch() {
		const image = this.image.replaceAll(this.randStr(), this.randStr());
		this.setBg(image);
		this.interval.next = this.randInt(1500, 5000);
	}
}