An ES module's interface is not a single value, but a set of named variables.

import ordinal from "ordinal"
import {days, months} from "date-names"

export function formatDate(date, format) {
	return format.replace(/YYYY|M(MMM)?|Do|dddd/g, tag => {
		if (tag == "YYYY") return date.getFullYear()
		if (tag == "M") return date.getMonth()
		if (tag == "MMMM") return months[date.getMonth()]
		if (tag == "D") return date.getDate()
		if (tag == "Do") return ordinal(date.getDate())
		if (tag == "dddd") return days[date.getDay()]
	})
}

Instead of calling a function to access a dependency you can use the special import keyword. Similarly, the export keyword is used to export things. It can appear in front of a variable, function, or class.

When there is a variable named default, it is treated as the module's main exported value. If you import a module like ordinal in this example, without braces around the name, you get it's default variable. Such modules can still export other variables alongside their default export.
export default ["Winter", "Spring", "Summer", "Autumn"]

You can also rename imported variables:
import {days as dayNames} from "date-names"

In nodejs you need to enable ES modules by setting "type": "module" in your package.json.