aurelia-polyfills/src/number.js

The minimal set of polyfills that the Aurelia platform needs to run on ES5 browsers.

if (typeof FEATURE_NO_ES2015 === 'undefined') {

Number.isNaN = Number.isNaN || function(value) {     
  return value !== value;
};

Number.isFinite = Number.isFinite || function(value) {
  return typeof value === "number" && isFinite(value);
};

} // endif FEATURE_NO_ES2015