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javascriptarraysfilterindexof

Selecting Items in array - Javascript - Using Filter method

Someone asked a question today about figuring out to select certain elements within an array from I to the end of the array and it made me wonder how to do that with the filter method.

One of the solutions that someone gave was to use slice and I understand that you're able to select from index to index, but how would you implement the filter method to do the same thing?

Example

let arr = ['bug', 'cat', 'dog', 'flea', 'bat', 'hat', 'rat'];

let newArr = arr.filter(element => element >= element.indexOf(3));
    
console.log(newArr);

This is what I came up with, it doesn't work, but the idea is to select all strings that have an index of 3 or greater and return them into another array.

Solution

  • The runtime passes the index to the filter callback:

    let newArr = arr.filter((element, index) => index >= 3);

    Performance-wise you're still making a new array and copying values, so it's about the same as .slice().