Create new object if it doesn’t exist, else update

I’m having quite some trouble handling objects and storing them as JSON.

What I’m trying to do is next:

1. parse json file

var links = JSON.parse([{"user1":{"username":"user1","data":"164"}},{"user2":{"username":"user2","status":0}}]);

2. If user1 exists, update the whole object with new data, ELSE create new object

  var key     =  dater['username']; //dynamic username strings

  var ACCOUNT =  {
                    username: key,
                    data: value, 
                    status:1
                }

if(links.hasOwnProperty(key)){

   links[key] = ACCOUNT;
   links=JSON.stringify(links);

   fs.writeFile('status.json', links, err => {
       // error checking
       if(err) throw err;

       console.log('Exists.. updating.');
   });
}else{  // ELSE create new entry

       links.push({[key]: ACCOUNT});
       newData= JSON.stringify(links);

       fs.writeFile('status.json', newData, err => {
           // error checking
            if(err) throw err;

             console.log('New user.. creating');
       });

}

As you can probably tell, the above doesn’t work as I’d want it to. I’m used with PHP arrays where I would simply do arrays with keys and directly update them without any ‘if/else’

Answer

const key = dater['username']; //dynamic username strings

const account = {
    username: key,
    data: value,
    status: 1,
};

const matchedItem = links.find((i) => i[key]);

if (matchedItem) {
    matchedItem[key] = account;
} else {
    links.push({ [key]: account });
}

console.log('links:::', links);

fs.writeFile('status.json', JSON.stringify(links), (err) => {
    if (err) throw err;

    console.log('New user.. creating');
});