JavaScript - get array element fulfilling a condition

Question

I\'m learning JavaScript using W3C and I didn\'t find an answer to this question.

I\'m trying to make some manipulations on array elements which fulfill some conditi

Answer 1

Write a generic function that accepts various conditions:

function array_only(arr, condition) {
    hold_test=[]
    arr.map(function(e, i) {if(eval(condition)){hold_test.push(e)}})
    return(hold_test)
    }

Example:

use_array = ['hello', 'go_there', 'now', 'go_here', 'hello.png', 'gogo.log', 'hoho.png']

Usage:

return only elements containing .log extension:

array_only(use_array, "e.includes('.log')")

[ 'gogo.log' ]

return only elements containing .png extension:

array_only(use_array, "e.includes('.png')")

[ 'hello.png', 'hoho.png' ]

return only elements NOT containing .png extension:

array_only(use_array, "!e.includes('.png')")

[ 'hello', 'go_there', 'now', 'go_here', 'gogo.log' ]

return elements containing set of extensions and prefixes:

array_only(use_array, "['go_', '.png', '.log'].some(el => e.includes(el))")

[ 'go_there', 'go_here', 'hello.png', 'gogo.log', 'hoho.png' ]

You can easily pass MULTIPLE CONDITIONS

return all png files that are less than 9 characters long:

array_only(use_array, "e.includes('.png') && e.length<9")

[ 'hoho.png' ]