CODEWITHSUNDEEP
javascriptnode.jslodash
Breedly
Breedly

Reputation: 14226

Lodash break from map/reduce on error?

If I have a function like _.transform.

Somewhere within the iteratee function I encounter an error; how do I exit from the _.transform function?

i.e.

{
  try {
    fs.readFileSync('dog_pics');
  } catch(e) {
    return;
  }
}

What about _.map? Which expects return statements.

Upvotes: 2

Views: 6067

Answers (2)

Andrey
Andrey

Reputation: 4050

_.transform callback can return false in order to stop iterating.

From lodash examples:

_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
});
// → [4, 9]

As you can see, iteration breaks on third step, when n === 3

_.map and _.reduce doesn't support iteration stopping

Upvotes: 13

Josh C.
Josh C.

Reputation: 4363

Since _.transform builds a new return object, returning without setting a pushing onto the result would allow you to "jump" out of that iteration.

(I haven't actually tested this code.)

Upvotes: 0

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