Sort the climbing grades.js

/*
Description:
My 5th kata, and 1st in a planned series of rock climbing themed katas.

In rock climbing (bouldering specifically), the V/Vermin (USA) climbing grades start at 'VB' (the easiest grade), and then go 'V0', 'V0+', 'V1', 'V2', 'V3', 'V4', 'V5' etc. up to 'V17' (the hardest grade). You will be given a list (lst) of climbing grades and you have to write a function (sort_grades) to return a list of the grades sorted easiest to hardest.

If the input is an empty list, return an empty list; otherwise the input will always be a valid list of one or more grades.

Please do vote, rank, and provide any feedback on the kata.
*/
function sortGrades(lst) {
    let arr = ['VB','V0', 'V0+','V1', 'V2', 'V3', 'V4', 'V5', 'V6', 'V7', 'V8', 'V9', 'V10', 'V11', 'V12', 'V13', 'V14', 'V15', 'V16', 'V17'];
    return lst.sort((a,b) => arr.indexOf(a) - arr.indexOf(b))
};