A couple of suggestions

[danimoh]

Hey Max,
while checking-out your project, I noticed some things that could be improved.
If you want, I can submit a pull request for these things.

notificationJS/notificationJS.js

Lines 38 to 39 in ee11974

	let content = document.createElement('div');
	let title = document.createElement('div');

Can be const

notificationJS/notificationJS.js

Line 40 in ee11974

content.innerHTML = this.info.title;

title.innerHTML = this.info.title;?

notificationJS/notificationJS.js

Lines 45 to 46 in ee11974

	if (this.info.link) {
	if (this.info.link.href) {

Can be joined into a single if.

notificationJS/notificationJS.js

Lines 55 to 56 in ee11974

	let description;
	description = document.createElement('div');

Can be simplified to const description = ...

notificationJS/notificationJS.js

Line 59 in ee11974

Object.assign(link.style, this.styles.link);

Should be moved to into the block where the link is created.

notificationJS/notificationJS.js

Line 80 in ee11974

let notification = this.notification;

Can be simplified to const notification = .... Or just this.notification can be used.

notificationJS/notificationJS.js

Lines 82 to 84 in ee11974

	setTimeout(function () {
	notification.outerHTML = "";;
	}, this.info.animation_duration * 1000 + 100);

setTimeout(() => notification.remove(), this.info.animation_duration * 1000 + 100)

notificationJS/notificationJS.js

Lines 99 to 100 in ee11974

	let body = document.getElementsByTagName('body')[0];
	body.append(notification_panel);

Can use document.body

notificationJS/notificationJS.js

Line 103 in ee11974

let anim_t = this.info.animation_duration * 1000;

The animation duration is configurable, however the opacity transition duration not adapted to this.info.animation_duration

notificationJS/notificationJS.js

Lines 111 to 118 in ee11974

	setTimeout(function () {
	notificationContainer.style.opacity = 0;
	}, display_t);
	//destroy
	setTimeout(function () {
	notificationContainer.remove();
	}, display_t + anim_t + 100);

The hiding logic could be moved into a hide method, which can then also be used in the close icon event listener.

notificationJS/notificationJS.js

Line 123 in ee11974

if (!this.info.debug) this.info.debug = true;

Makes the flag kind of unnecessary 😄

notificationJS/notificationJS.js

Lines 131 to 133 in ee11974

	if (this.info.link) {
	if (!this.info.link.href)
	if (this.info.debug)

These ifs can be joined.