(function(root) {
  'use strict';

  function isBase64(v, opts) {
    if (v instanceof Boolean || typeof v === 'boolean') {
      return false
    }
    if (!(opts instanceof Object)) {
      opts = {}
    }
    if (opts.hasOwnProperty('allowBlank') && !opts.allowBlank && v === '') {
      return false
    }

    var regex = '(?:[A-Za-z0-9+\\/]{4})*(?:[A-Za-z0-9+\\/]{2}==|[A-Za-z0-9+\/]{3}=)?';

    if (opts.mime) {
      regex = '(data:\\w+\\/[a-zA-Z\\+\\-\\.]+;base64,)?' + regex
    }

    if (opts.paddingRequired === false) {
      regex = '(?:[A-Za-z0-9+\\/]{4})*(?:[A-Za-z0-9+\\/]{2}(==)?|[A-Za-z0-9+\\/]{3}=?)?'
    }

    return (new RegExp('^' + regex + '$', 'gi')).test(v);
  }

  if (typeof exports !== 'undefined') {
    if (typeof module !== 'undefined' && module.exports) {
      exports = module.exports = isBase64;
    }
    exports.isBase64 = isBase64;
  } else if (typeof define === 'function' && define.amd) {
    define([], function() {
      return isBase64;
    });
  } else {
    root.isBase64 = isBase64;
  }
})(this);