常用js判断方法[收藏]

转贴

isNull: function(a){      return a === null;  },  isUndefined: function(a){      return a === undefined;  },  isNumber: function(a){      return typeof a === 'number';  },  isString: function(a){      return typeof a === 'string';  },  isBoolean: function(a){      return typeof a === 'boolean';  },  isPrimitive: function(b){      var a = typeof b;      return !!(b === undefined || b === null || a == 'boolean' || a == 'number' || a == 'string');         },  isArray: function(a){      return proto_obj.toString.call(a) === '[object Array]';  },  isFunction: function(a){      return proto_obj.toString.call(a) === '[object Function]';  },  isPlainObject: function(o){      if (!o || o === win || o === doc || o === doc.body) {          return false;      }      return 'isPrototypeOf' in o && proto_obj.toString.call(o) === '[object Object]';          },  isWindow: function(o){      return o && typeof o === 'object' && 'setInterval' in o;  },  isEmptyObject: function(o){      for(var a in o) {      return false;      }      return true;  }