Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript JavaScript Array Iteration Methods Combining Array Methods Combining filter() and reduce()

Posted by gerardo keys
gerardo keys
14,292 Points

Not understanding the .filter and .reduce here.

.reduce((highest, product) => { if (highest.price > product.price)

If highest is the accumulator in this function what is it starting at? In the if statement you have if(highest.price > product.price) ... I'm really having trouble understanding what highest.price is supposed to be or represent. How is it finding the highest price?

1 Answer

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

When "reduce" has only one argument (the callback function), the accumulator starts as the first item from the array. Since in the video example, it is chained on a "filter" call, it would be the first item returned by "filter".

Since each element in the array is an object with a "price" property, "highest.price" is the price value of the item determined to be largest.

gerardo keys
gerardo keys
14,292 Points

Omg ty, thats exactly what I was wondering!! You cleared it up perfect!