使用功能和括号符号将属性添加到对象

Question

I have an assignment on a basic javascript class that I'm taking and I can't seem to get this to work. I have this unit test that was given to me:

describe('AddSixthProperty', function() {
      it('should add a food property with the value of bbq using bracket notation', function() {
        expect(objects.addSixthProperty()['food']).to.equal('BBQ');
      });
    });

I was given an empty function:

// don't touch this line
var mysticalAnimal = objects.mysticalAnimal();
function addSixthElement(){

return
}

So I tried this:

var mysticalAnimal = objects.mysticalAnimal();
objects.addSixthProperty = function(){
  mysticalAnimal['food'] = "bbq";
  return mysticalAnimal["food"];
};

It doesn't work. Our test page doesn't pass that. Any help is greatly appreciated!

Thanks in advance!

Answer 1

You're returning mysticalAnimal['food'] , and then the test tries to access ['food'] again, so it ends up accessing 'bbq'['food'] , which is undefined . You need to just return mysticalAnimal , as well as get all your letter cases right. Here's a little proof of concept:

 var objects = (function() { var animal = { mystical: true }; return { mysticalAnimal: function() { return animal; } }; })(); var mysticalAnimal = objects.mysticalAnimal(); objects.addSixthProperty = function(){ mysticalAnimal['food'] = "bbq"; return mysticalAnimal; }; var capturedAnimal = objects.addSixthProperty(); document.getElementById('result').innerText = capturedAnimal['food']; 

 <p id="result" /> 

Answer 2

Here is the function:

 var mysticalAnimal = objects.mysticalAnimal(); objects.addSixthProperty = function(){ mysticalAnimal['food'] = "BBQ"; return mysticalAnimal; }; // Test the function console.log(objects.addSixthProperty()['food'])