Александр

const elements = document.querySelectorAll('tag_1, tag_2');
elements.forEach(element => {
	if (element.tagName === 'TAG_1') {
		// Do something
	}

	if (element.tagName === 'TAG_2') {
		// Do something
	}
});

class Select {
	constructor({
		selector,
		label,
		url,
		onOpen,
		onClose
	}) {
		this.container = document.querySelector(selector);
		this.label = label;
		this.url = url;
		this._onOpen = onOpen;
		this._onClose = onClose;

		...
	}

	...

	open() {
		...

		if (this._onOpen !== undefined) {
			this._onOpen();
		}
	}

	close() {
		...

		if (this._onClose !== undefined) {
			this._onClose();
		}
	}
}

const svg = document.querySelector('#svg');
const item = svg.querySelector('#rect');

const size = svg.getBoundingClientRect();
const viewBox = svg
  .getAttribute('viewBox')
  .split(/\s+/g)
  .map(entry => Number(entry));

const normalize = (min, max, value) => {
  return (value - min) / (max - min);
};

const lerp = (min, max, value) => {
  return (1 - value) * min + value * max;
};

const map = (minSource, maxSource, minDestination, maxDestination, value) => {
  return lerp(minDestination, maxDestination, normalize(minSource, maxSource, value));
};

svg.addEventListener('mousemove', event => {
  item.setAttribute(
    'cx',
    map(0, size.width, viewBox[0], viewBox[2], event.offsetX)
  );
  item.setAttribute(
    'cy',
    map(0, size.height, viewBox[1], viewBox[3], event.offsetY)
  );
});

array.filter(entry => (
	entry.name !== 'Имя' &&
	entry.price !== 'Цена'
));

const timestamp = (year, month = 1, day = 1) => new Date(year, month - 1, day).getTime();

const entries = [
	{
		type: 'error',
		date: timestamp(2020, 4, 30)
	},
	{
		type: 'log',
		date: timestamp(2020, 4, 29)
	},
	{
		type: 'info',
		date: timestamp(2020, 4, 25)
	}
];

const date = new Date();
const today = timestamp(date.getFullYear(), date.getMonth() + 1, date.getDate());
const interval = 24 * 60 * 60 * 1000;

const entry = entries.find(entry => (entry.date >= today && entry.date <= today + interval));

console.log(entry); // { type: 'error', date: 1588183200000 }

window.addEventListener('scroll', event => {
  if (scrollY + innerHeight === document.body.scrollHeight) {
    // Code here
  }
});

const $humans = await data.response.items;

if($humans.some(entry => entry.hasOwnProperty('last_seen'))) {
    // Всё еще массив, так что надо еще найти тот элемент, в котором есть этот ключ
} else {
    // Всё еще массив
}

const $humans = await data.response.items;
const $human = $humans.find(entry => entry.hasOwnProperty('last_seen'));

if($human !== undefined) {
    // Первый элемент из массива с ключём last_seen
} else {
    // Какой-то код
}