In https://javascript.info/array-methods#filter-range, I would suggest saying "...looks for elements with values higher or equal to a and lower or equal to b" rather than the current "...looks for elements between a and b".

Right now it sounds like "between" is referring to indices. The solution I wrote initially looked like this:

let filterRange = (arr, a, b) => {
    if (b > arr.length) return arr.slice(a);
    else return arr.slice(a, b);
};