JS Array functions in Google Spreadsheets

Code.gs

function JSMAP(data, fn) {
  return data.map(eval(fn));
}

function JSFILTER(data, fn) {
  return data.filter(eval(fn));
}

function JSREDUCE(data, fn, start) {
  return data.reduce(eval(fn), eval(start));
}

/*
  example usage: replace all Joe's with Jane's
  =JSMAP(A1:A20; "(row) => row[0].replace('Joe', 'Jane')")
*/