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JavaScript React by Example Building the Application Removing Names From the List

Wen Jie Lim
Wen Jie Lim
1,264 Points
Posted by Wen Jie Lim
Wen Jie Lim
1,264 Points

Why use .slice instead of .filter?

To me, using Array.slice() in this case is a little gimmicky because you have to call it twice, plus have to think the logic through.

We could just use Array.filter() and do like:

removeGuestAt = indexToChange => 
  this.setState({
    guests: this.state.guests.filter((guest, index) => index!== indexToRemove)
})

Just out of curiosity, does Array.slice() have any advantage over Array.filter(), say, performance?

1 Answer

Alex Acker
Alex Acker
1,133 Points
Alex Acker
Alex Acker
1,133 Points

I think the one performance disadvantage of using filter over slice is that the former has to loop through each item in the array before it finishes. Slicing on large heavy arrays would probably serve as preference here, however with smaller amounts, the performance would probably be minor if noticeable at all. Quick read a user did testing the two in the link below.

https://medium.com/@justintulk/javascript-performance-array-slice-vs-array-filter-4573d726aacb

As highlighted at the end of the article, I think what's critical regarding any final code decision is both readability and the ability to scale. I actually wrote my solution using splice in which I utilized the 'prevState' callback to manipulate the array and then return it again.