WebStorm does not autocomplete properties of object which returned by a function (many nodejs modules are without autocomplete).

// If function returs an object created on the fly, autocomplete will work.
function fun1() {
 return {
  aaaa: 13
 };
}

var obj1 = fun1();
//obj1.aa // Autocomplete works.

var obj2 = {
 bbbb: 15
};

obj2.cccc = 16;

// No creation on the fly, autocompletion does not work.
function fun2() {
 return obj2;
}
var obj3 = fun2();

//obj3.bb // Autocomplete does not work. You will laugh, but SublimeText will suggest variants (bbbb, aaaa, etc).


// Many Node.js modules use such an approach:

var innerObject = {};
innerObject.func1 = function(){};
innerObject.prop1 = 'bla bla bla';
module.exports = function() {
  return innerObject;
}

//And WebStorm in such case does not provide autocompletion. A programmer have to open module source and search for object names by hands, how so :(.