JavaScript - get array element fulfilling a condition

user_324922 0
Viewed 144878

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 condition.

Is there a way to do it other than running on the array elements in for loop? Maybe something like (in other languages):

foreach (object t in tArray)
   if (t follows some condition...) t++;

another thing, sometimes I want to use the element's value and sometimes I want to use it as a reference. what is the syntactical difference?

As well, I'll be happy for recommendations on more extensive sites to learn JavaScript from. thanks

conditional-statements arrays javascript
10 Answers
user_6339690

You can use Array.prototype.find, wich does exactly what you want, returns the first element fullfilling the condition. Example:

> ([4, {a:7}, 7, {a:5, k:'r'}, 8]).find(o => o.a == 5)

{a:5, k:'r'}
user_33005080

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' ]

user_16395940

I am joining in late, but I have an interesting solution. If you only want to filter a single element i.e the first element that satisfies the condition, you could use the JS find function.

myArray.find(x => x > 5)
user_88633980

Problem:

I need to know if a client set exists for any PJ client.

Solution:

function deveExibirLista(lst: Clientes[]){
    return lst.some(cli => cli.Documento === 14);
}

It's return boolean

user_77941830
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