source: Dev/trunk/node_modules/should/lib/util.js

/**
 * Check if given obj just a primitive type wrapper
 * @param {Object} obj
 * @returns {boolean}
 * @api private
 */
exports.isWrapperType = function(obj) {
    return isNumber(obj) || isString(obj) || isBoolean(obj);
}

/**
 * Merge object b with object a.
 *
 *     var a = { foo: 'bar' }
 *       , b = { bar: 'baz' };
 *
 *     utils.merge(a, b);
 *     // => { foo: 'bar', bar: 'baz' }
 *
 * @param {Object} a
 * @param {Object} b
 * @return {Object}
 * @api private
 */

exports.merge = function(a, b){
  if (a && b) {
    for (var key in b) {
      a[key] = b[key];
    }
  }
  return a;
};

function isNumber(arg) {
  return typeof arg === 'number' || arg instanceof Number;
}

exports.isNumber = isNumber;

function isString(arg) {
  return typeof arg === 'string' || arg instanceof String;
}

function isBoolean(arg) {
  return typeof arg === 'boolean' || arg instanceof Boolean;
}
exports.isBoolean = isBoolean;

exports.isString = isString;

function isBuffer(arg) {
  return typeof Buffer !== 'undefined' && arg instanceof Buffer;
}

exports.isBuffer = isBuffer;

function isDate(d) {
  return isObject(d) && objectToString(d) === '[object Date]';
}

exports.isDate = isDate;

function objectToString(o) {
  return Object.prototype.toString.call(o);
}

function isObject(arg) {
  return typeof arg === 'object' && arg !== null;
}

exports.isObject = isObject;

function isRegExp(re) {
  return isObject(re) && objectToString(re) === '[object RegExp]';
}

exports.isRegExp = isRegExp;

function isNullOrUndefined(arg) {
  return arg == null;
}

exports.isNullOrUndefined = isNullOrUndefined;

function isArguments(object) {
  return objectToString(object) === '[object Arguments]';
}

exports.isArguments = isArguments;

exports.isFunction = function(arg) {
  return typeof arg === 'function' || arg instanceof Function;
};

function isError(e) {
  return isObject(e) && objectToString(e) === '[object Error]';
}
exports.isError = isError;