How to rewrite code for IE 11?

Question

JavaScript

Tell me how to properly remake this code for IE 11. It swears at invalid characters and breaks all js.

let vh = window.innerHeight * 0.01;
    document.documentElement.style.setProperty('--vh', `${vh}px`);

    window.addEventListener('resize', () => {
        let vh = window.innerHeight * 0.01;
        document.documentElement.style.setProperty('--vh', `${vh}px`);
    });

Answer 1

vh + 'px'
and the arrow function needs to be changed to a regular one

Answer 2

As far as I remember, IE does not support ES6 at all (this applies to both arrow functions and const / let and template strings. It's easier to run the code through babel.