1 判断属性
71 -81
var hasOwnProperty = Object.prototype.hasOwnProperty;
/**
 * Check whether the object has the property.
 *
 * @param {Object} obj
 * @param {String} key
 * @return {Boolean}
 */

function hasOwn(obj, key) {
  return hasOwnProperty.call(obj, key);
}

 
2 判断传进来的值是否定义 定义转为字符串 未定义转为空(108 - 118)
function _toString(value) {
  return value =http://www.mamicode.com/= null ? ‘‘ : value.toString();>