Assign object keys to another object's keys dynamically

Question

I have an array called viewObject.terms. This array can contain up to 3 items, I need to iterate through this array and save the values into a data object.

ie:

data.term_id_1 = viewObject.terms[0].term_id
data.ticker_1 = viewObject.terms[0].its_ticker

This is what I first tried, but I get the error: Cannot set property '0' of undefined

for (var i=0; i<viewObject.terms.length; i++) {
 data.term_id_[i+1] = viewObject.terms[i].term_id;
 data.ticker_[i+1] = viewObject.terms[i].its_ticker;
}

TypeError

---

So for the moment, I'm just using a switch case to handle this currently (albeit in a super ugly way):

if (viewObject.terms.length > 0) {
 switch(viewObject.terms.length) {
 case 1:
 data.term_id_1 = viewObject.terms[0].term_id;
 data.ticker_1 = viewObject.terms[0].its_ticker;
 break;
 case 2:
 data.term_id_1 = viewObject.terms[0].term_id;
 data.ticker_1 = viewObject.terms[0].its_ticker;
 data.term_id_2 = viewObject.terms[1].term_id;
 data.ticker_2 = viewObject.terms[1].its_ticker;
 break;
 case 3:
 data.term_id_1 = viewObject.terms[0].term_id;
 data.ticker_1 = viewObject.terms[0].its_ticker;
 data.term_id_2 = viewObject.terms[1].term_id;
 data.ticker_2 = viewObject.terms[1].its_ticker;
 data.term_id_3 = viewObject.terms[2].term_id;
 data.ticker_3 = viewObject.terms[2].its_ticker;
 break;
 }
}

• Brett Caswell: as phrased, this seems more akin to a stackoverflow type question, because you're receiving an error (exception)... but it's likely answered already, and so it'll just be flagged as a duplicate.

Answer 1

Another solution to the problem could be expressed using Array.prototype.forEach(), as the following:

viewObject.terms.forEach(function(term, index){
 data['term_id_' + (index + 1)] = term.term_id;
 data['ticker_' + (index + 1)] = term.its_ticker;
});

• KingCodeFish: This one is more elegant than the author's own conclusion. votes++; :-)
• Brett Caswell: yeah, that's one way of doing it, but the link you referenced actually provides a sample on how to make a CopyTo function on objects.. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

Answer 2

Just figured this out! Hope my answer helps someone else:

for (var i=0; i<viewObject.terms.length; i++) {
 data['term_id_'+(i+1)] = viewObject.terms[i].term_id;
 data['ticker_'+(i+1)] = viewObject.terms[i].its_ticker;
}

This is how you dynamically name and iterate keys inside of an object