How can I check that two objects have the same set of property names?

Question

I am using node, mocha, and chai for my application. I want to test that my returned results data property is the same "type of object" as one of my model objects (Very similar to chai's instance). I just want to confirm that the two objects have the same sets of property names. I am specifically not interested in the actual values of the properties.

Let's say I have the model Person like below. I want to check that my results.data has all the same properties as the expected model does. So in this case, Person which has a firstName and lastName.

So if results.data.lastName and results.data.firstName both exist, then it should return true. If either one doesn't exist, it should return false. A bonus would be if results.data has any additional properties like results.data.surname, then it would return false because surname doesn't exist in Person.

This model

function Person(data) {   var self = this;   self.firstName = "unknown";   self.lastName = "unknown";    if (typeof data != "undefined") {      self.firstName = data.firstName;      self.lastName = data.lastName;   } } 

Answer 1

You can serialize simple data to check for equality:

data1 = {firstName: 'John', lastName: 'Smith'}; data2 = {firstName: 'Jane', lastName: 'Smith'}; JSON.stringify(data1) === JSON.stringify(data2) 

This will give you something like

'{firstName:"John",lastName:"Smith"}' === '{firstName:"Jane",lastName:"Smith"}' 

As a function...

function compare(a, b) {   return JSON.stringify(a) === JSON.stringify(b); } compare(data1, data2); 

EDIT

If you're using chai like you say, check out http://chaijs.com/api/bdd/#equal-section

EDIT 2

If you just want to check keys...

function compareKeys(a, b) {   var aKeys = Object.keys(a).sort();   var bKeys = Object.keys(b).sort();   return JSON.stringify(aKeys) === JSON.stringify(bKeys); } 

should do it.