How to optimize this for loop function?

Question

var tickers = [];

for (var i=0; i<reportsArray.length; i++) {
    tickers.push(reportsArray[i].ticker);
}

Is there a way to replicate the above using the fastest / most efficient way in lodash.

This is what the objects may look like in the reportsArray:

{
    added_epoch: 1452873186
    details: ""
    reason: ""
    term: "Google rocks!"
    ticker: "GOOG"
    user_id: 1346753
    username: "leon"
}

Nothing in lodash is going to be faster than what you're doing but have you looked into use map? There's also a native implementation. — Mike Cluck
– Mike Cluck, Commented Feb 1, 2016 at 20:58
I agree with @MikeC, but you can verify by creating tests with realistic data on jsperf.com — Noel
– Noel, Commented Feb 1, 2016 at 21:01

Prashant · Accepted Answer · 2016-02-01 20:58:07Z

6

var tickers = reportsArray.map(function (report) {
    return report.ticker;
});

And, if you want to do this in Lodash anyway, use _.map() to achieve the same result.

var tickers = _.map(reportsArray, function (report) {
    return report.ticker;
});

answered Feb 1, 2016 at 20:58

Prashant

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1 Comment

Thanks! I renamed my title to better fit, also great answer.

Lukáš Havrlant · Accepted Answer · 2016-02-02 17:48:03Z

1

You can use just

var tickers = _.map(reportsArray, 'ticker');

answered Feb 2, 2016 at 17:48

Lukáš Havrlant

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