How to get property of an object to a variable in Javascript?

Question

Learning from Codecademy. I have to get property of an object to a variable( not property value). This is messing with my brain from an hour.

Here is the code (I messed up a bit to find solution. Please use comments understand it correctly. I am confused to ask) SCREENSHOT: http://prntscr.com/bcj94x

var james = {
job: "programmer",
married: false
};

// set to the first property name of "james"
var aProperty = james["job"];

// print the value of the first property of "james" 
// using the variable "aProperty"
console.log(james["job"]);
console.log(aProperty);

I am getting: this in the console when run the script

programmer 
programmer

Thanks

Everyone seems fine .What's your problem ? What is your question ? — Abhishek Panjabi
– Abhishek Panjabi, Commented Jun 5, 2016 at 7:44
@AbhishekPanjabi i don't understand how he got "Programmer" when the value is "programmer" — Tilak Madichetti
– Tilak Madichetti, Commented Jun 5, 2016 at 7:45
I need to get property of the object to aProperty. Not the property value. — Dhanu AT
– Dhanu AT, Commented Jun 5, 2016 at 7:45
You mean you need to get 'job' to aProperty? And then do console.log(james[aProperty]); console.log(aProperty); and get results 'job' 'programmer' correspondingly? — Azamantes
– Azamantes, Commented Jun 5, 2016 at 7:46

Thomas Junk · Accepted Answer · 2016-06-05 07:52:45Z

1

What result did you expect?

Defining your object using with the Javascript Object Notation (JSON for short) results in an object with two properties job and married.

This object is referenced via the variable james. Everytime you are using james in your code, you are dealing with the referenced object.

The same goes for var aProperty = james["job"];. Everytime, when your variable aProperty is used, it refers to the job property of the object referenced with james.

It is like saying: »From now on, when I say "aProperty", I mean the job-property of james«.

Your comment is a bit misleading:

// set to the first property name of "james"

In this case job is the first property. Correct would be set to the property named job.

From the above should the result be not unexpected.

console.log(james["job"]);
console.log(aProperty);

Both print programmer because aProperty is equivalent to james["job"] like saying Thomas or the person who wrote this is referencing to me and thus equivalent.

answered Jun 5, 2016 at 7:52

Thomas Junk

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2 Comments

Dhanu AT Over a year ago

NO. That is not a miss leading comment. That is the exact comment they put in the code to give me instruction. I need to get 'job' as the result when I call aProperty.

Thomas Junk Over a year ago

It is the first by accident. If you change the order of job and married, the reference still holds. but it references not the first property.

Gerardo Furtado · Accepted Answer · 2016-06-05 08:06:38Z

0

If you want to get the key associated to a given value, you can do this:

var james = {
  job: "programmer",
  married: false
};

Object.prototype.getKey = function (value){
  for(var property in this){
     if(this.hasOwnProperty(property)) {
          if(this[property] === value )
              return property;
          }
     }
};

console.log(james.getKey('programmer'));

It will give you "job".

So, using this function, you can simply write:

 var aProperty = james.getKey('programmer');

edited Jun 5, 2016 at 8:06

answered Jun 5, 2016 at 7:59

Gerardo Furtado

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Comments

Webeng · Accepted Answer · 2016-06-05 08:13:49Z

0

You can use a for in loop to put the key values of the key : value pairs found in your james object inside an array called aProperty, and then print out your results in the console.

var james = {
job: "programmer",
married: false
};


var aProperty = [];
for (myvar in obj) {
 if (obj.hasOwnProperty(myvar)) {
   aProperty.push(myvar);
 }
}

console.log(aProperty[0]);
console.log(aProperty[1]);

answered Jun 5, 2016 at 8:13

Webeng

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