index.js
function parse() {
  var msie = /MSIE.(\d+)/i.exec(ua);
  var rv = /Trident.+rv:(\d+)/i.exec(ua);
  var version = msie || rv || undefined;
  return version ? +version[1] : version;
}
function parse() {
  var msie = /MSIE.(\d+)/i.exec(ua);
  var rv = /Trident.+rv:(\d+)/i.exec(ua);
  var version = msie || rv || undefined;
  return version ? +version[1] : version;
}
function parse ( ) { var msie = / MSIE.(\d+) / i . exec ( ua ) ; var rv = / Trident.+rv:(\d+) / i . exec ( ua ) ; var version = msie || rv || undefined ; return version ? + version [ 1 ] : version ; }
Get IE major version number

@return {Number}
@api private
Get IE major version number