Highlighting numbers

Highlighting numbers in table

var changeColorCell = function (number) {
  var negativeNumClass = ".negative",
      positiveNumClass = ".positive";
if (Object.is(Math.sign(parseFloat(number)), -0)) {
    return negativeNumClass;
  } else if (Object.is(Math.sign(parseFloat(number)), 0)) {
    return positiveNumClass;
  } else if (Object.is(Math.sign(parseFloat(number)), 1)) {
    return positiveNumClass;
  } else if (Object.is(Math.sign(parseFloat(number)), -1)) {
    return negativeNumClass;
  } 
}