We spent a lot of time optimizing our code to increase performance of UX of our app. But still, we thought it was not up to the mark as it was taking little more time to load UI whereas getting the response from API was in less than a second. We felt something was wrong.

We decided to check on a particular page what part of code is taking a lot of time using performance panel from chrome dev tool.

We were all astonished after looking at the result. It was_.findWhere which was taking a lot of time. We use underscore.js (a javascript library which provides helper functions) throughout our app. We used_.findWhere in some places where there is a better alternative which executes fast.

So is it bad to use_.findWhere?

The answer isNO.
There is nothing wrong in using_.findWhere, but you also need to know when to not use it.

Suppose you have an array of objects, let's sayexample_array, you want to find a particular object in that array only once. Then using_.findWhere is good.

But you have a scenario where you want to find different objects fromexample_array in different places of your controller, then using_.findWhere would be a bad idea. Why do you want to parse the same array by looping it again and again?

Instead, index the array and get the object immediately. You will get your required result in no time.

When we executed this change by replacing_.findWhere with indexed objects. Performance of our page was improved. The page was loading noticeably faster than before 🙂

So be sure when to use_.findWhere and when not to use.

I hope this post helps 🙂