Implement a function in javascript using map

Question

I have to implement the helloProperties(obj) function. This function takes as parameter obj an object like this one:

{
    john: 12,
    brian: true,
    doe: 'hi',
    fred: false
}

And returns an array containing its property names, prefixed with "Hello-", like this:

['Hello-john', 'Hello-brian', 'Hello-doe', 'Hello-fred']

obj is always defined and is always a JavaScript object.

So i did that code below:

function helloProperties(obj){
    var array=Object.keys(obj).map(function(cle){
        return "Hello-"+cle;
    });
}
var obj={
    john:12,
    brian:true,
    doe:'hi',
    fred:false
}
console.log(helloProperties(obj));

question from:https://stackoverflow.com/questions/65713128/implement-a-function-in-javascript-using-map

Answer 1

You need to return the array variable from the function:

function helloProperties(obj) {
  // Handle null obj per the request in the comments.
  if (obj === null) return [];

  var array = Object.keys(obj).map(function(cle) {
    return "Hello-" + cle;
  });

  return array;
}

var obj = {
  john: 12,
  brian: true,
  doe: 'hi',
  fred: false
}

console.log(helloProperties(obj));