JavaScript中的isXX系列

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; }