Javascript ternary operator (?:) change and return object in single block

Question

Is it possible inside ?: change dictionary and return this dictionary in the same block. Something like this a > b ? <dict['c'] = 'I'm changed', return dict> : <some other code>;

I need this inside map function. Something like this:

var a = [...]
a.map((itm) => return itm.isComposite ? itm[key] = transform(itm[data]); return itm : transform(itm))

Answer 1

Yes, it's possible by using the comma operator:

a > b ? (dict['c'] = "I'm changed", dict) : <some other code>;

The comma operator evaluates all of its operands and returns the value of the last (rightmost) one.

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However, a proper if statement might be the more readable solution here, which is why I'd recommend you use it instead of constructing a conditional ("ternary") expression.

Answer 2

The comma operator should be enough. No need to use the return keyword.

var result = (a > b
  ? (dict['c'] = "I'm changed", dict)
  : <some other code> );

If you want to return the result then it goes outside the expression:

return (a > b
  ? (dict['c'] = "I'm changed", dict)
  : <some other code> );

That said, I would prefer using if statements for this problem. In my opinion, long ternary expressions are hard to read.