'Data type' problem when querying a JSON object

Towards the end of this video, Andrew suggests a challenge where in the console we can enter node app.js JavaScript chalkers. So the challenge is to modify the current code to achieve this.

1. Recognise that the 3rd entry is now a topic and not a user.
2. Recognise that users will be 4th entry onwards.
3. Modify the print message so that the points read are for the subject entered in the console.

1 & 2 I have done, but with 3 I am either very close or miles away.

So at the console I have entered: node app.js JavaScript chalkers

It correctly shows: chalkers has 209 total badge(s) and 5946 points in JavaScript

but this is because I have not yet been able to change the 'printMessage' line.

Here is the code extract.

// Parse the data

const profile = JSON.parse(body);
const topic = process.argv.slice(2)[0];
const subject = `profile.points.${topic}`;

// Print the data

printMessage(username, profile.badges.length, profile.points.JavaScript);

console.log(topic); // JavaScript  
console.log(typeof topic); // string 
console.log(username); // chalkers 
console.log(typeof username); // string 
console.log(profile.badges.length);// 209  
console.log(typeof profile.badges.length);//  number
console.log(profile.points.JavaScript);// 5946 
console.log(typeof profile.points.JavaScript);// number
console.log(subject);// profile.points.JavaScript
console.log(typeof subject);// string

So in the printMessage line, I had hoped to be able to replace profile.points.JavaScript with subject but the data type of subject is wrong.

Is there a simple data conversion I need to make or is the approach wrong?