Underscore Mixin for IE (Internet Explorer) browser detection.

isIE.mixin.js

// https://jsfiddle.net/danrichards/16mxh9th/

_.mixin({
  isIE: function(mixed) {
    if (_.isUndefined(mixed)) {
      mixed = [/MSIE\s7\./, /MSIE\s8\./, /MSIE\s9\./, /MSIE\s10\./, /Trident.*rv\:11\./];
    } else if (_.isArray(mixed)) {
      mixed = mixed.map(function(browser) {
        return new RegExp('MSIE\s'+browser.toString()+'\.', 'g');
      });
    } else if (_.isNumber(mixed) ) {
      switch (mixed) {
        case 11:
          mixed = [new RegExp('Trident.*rv\:11\.', 'g')];
          break;
        default:
          mixed = [new RegExp('MSIE\s'+mixed.toString()+'\.', 'g')];
      }
    }

    if (mixed.length == 0) {
      return false;
    }

    return mixed.reduce(function (previous, current, index) {
      return previous + (!! window.navigator.userAgent.match(current) ? 1 : 0);
    }, null) > 0;
  }
});

console.log(_.isIE());
console.log(_.isIE([7,8,9]));
console.log(_.isIE(11));