How to compare specific items in array inside of basic lodash loop

Question

This is the basic JavaScript for loop I'm trying to replace:

for (var i=0; i<tickers.length; i++) {
    if (tickers[i].ticker === selectedTicker) {
        selectTicker('portfolio', tickers[i]);
        break;
    }
}

Here is the lodash version

_.times((tickers.length), function() {
    if (tickers[i].ticker === selectedTicker) {
        selectTicker('portfolio', tickers[i]);
        return;
    }
});

Obviously this errors out currently, because there is no [i] variable set in the lodash version.

The lodash version is much more readable imho, just do this many times the length of my tickers array.

However I need to compare the ticker of each object to the selectedTicker.

UPDATE: Adding screenshot and link to prove to some asking that _lodash is faster than native Javascript.

http://jsperf.com/forloop-vs-each-from-lodash

Can you also add the jsperf comparison of _.find and _.filter/Native .filter? — Tushar
– Tushar, Commented Feb 17, 2016 at 3:56

Tushar · Accepted Answer · 2016-02-12 17:59:07Z

2

You can use _.find()

var ticker = _.find(tickers, {'ticker': selectedTicker});

// `find()` returns an object if the element is found in array
// it returns `undefined` if not found
if (ticker) {
    // If element found in the array call the function
    selectTicker('portfolio', ticker);

    // return; // To return from the function
}

edited Feb 12, 2016 at 17:59

answered Feb 12, 2016 at 17:26

Tushar

87.4k21 gold badges164 silver badges182 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Leon Gaban Over a year ago

Ah thanks! Nice! This found it, however now I need to tell the selectTicker function which item in tickers to pass in. How would you accomplish that here?

Tushar Over a year ago

@LeonGaban The find method returns object or undefined. You can use if (foundResult) { selectTicker(foundResult.key) }. In case, to send more than one elements from object, you can use _.pick() or _.omit

Leon Gaban Over a year ago

Thanks again, I'm trying that now, however it has to loop through all items in my Array before finishing, I want it to stop as soon as the foundResult has been found and the next function runs. However foundResult always shows true, and the return statement doesn't break the loop in this case.

Tushar Over a year ago

@LeonGaban You don't need the loop to get the matching object from array, just use _.find. Just use return after function call.

Leon Gaban Over a year ago

Ok sorry I misunderstood, I understand now thanks for the explanation. +1

jmcgriz · Accepted Answer · 2016-02-12 17:30:31Z

1

You need to pass i into the callback in the lodash function. This should work:

_.times((tickers.length), function(i) {
    if (tickers[i].ticker === selectedTicker) {
      selectTicker('portfolio', tickers[i]);
      return;
    }
});

Also, if you're able to use es6 syntax, you can achieve the same result by using filter

var ticker = tickers.filter(t => t.ticker === selectedTicker)[0];
if(ticker){
  selectTicker('portfolio', ticker);
}

answered Feb 12, 2016 at 17:30

jmcgriz

3,3981 gold badge11 silver badges16 bronze badges

Comments

Piotr Białek · Accepted Answer · 2016-02-12 17:30:31Z

1

You have to add an argument to the function:

_.times((tickers.length), function( i ) {
    if (tickers[i].ticker === selectedTicker) {
        selectTicker('portfolio', tickers[i]);
        return;
    }
});

answered Feb 12, 2016 at 17:30

Piotr Białek

2,7571 gold badge19 silver badges27 bronze badges

Collectives™ on Stack Overflow

How to compare specific items in array inside of basic lodash loop

3 Answers 3

5 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

5 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related