Need to remove string from an Array [duplicate]

Question

I have an array inside a for loop like this:

var arr = ["abc", "5", "city", "2", "area", "2", "max", "choice"];

And I need only number like this:

var arr = ["5","2","2"];

So can someone please help here.

Those "5", "2", and "2" are still strings

VLAZ
– VLAZ

2019-06-19 14:27:20 +00:00
Commented Jun 19, 2019 at 14:27 — VLAZ
– VLAZ, Commented Jun 19, 2019 at 14:27

Nina Scholz · Accepted Answer · 2019-06-19 14:57:44Z

3

Another approach by using a converted number to a string and compare with the original value.

var array = ["abc", "5", "city", "2", "area", "2", "max", "choice"],
    result = array.filter(v => (+v).toString() === v);

console.log(result);

Just shorter approach with isFinite

var array = ["abc", "5", "city", "2", "area", "2", "max", "choice"],
    result = array.filter(isFinite);

console.log(result);

While tagged with underscore.js, you could use the filtering and callback from underscore.

var array = ["abc", "5", "city", "2", "area", "2", "max", "choice"],
    result = _.filter(array, _.isFinite);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"></script>

edited Jun 19, 2019 at 14:57

answered Jun 19, 2019 at 14:34

Nina Scholz

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3 Comments

adiga Over a year ago

If there are any trailing zeros in decimal like "2.10" this won't work

alexr89 Over a year ago

isFinite() is a great way to do this

zfrisch Over a year ago

I wasn't aware of isFinite coercing before determining numbers. Very useful! +1

Andy · Accepted Answer · 2019-06-19 16:34:17Z

1

filter out the strings that are integers when they're coerced to one:

var arr = ["abc", "5", "city", "2", "", "area", "2", "max", "choice"];

const out = arr.filter(el => (
  el !== '' && Number.isInteger(Number(el)))
);

console.log(out)

edited Jun 19, 2019 at 16:34

answered Jun 19, 2019 at 14:28

Andy

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2 Comments

MauriceNino Over a year ago

Number.isInteger(+"") returns true too.

Andy Over a year ago

Nice catch. Fixed.

user4676340 · Accepted Answer · 2019-06-19 14:28:52Z

0

var arr = ["abc", "5", "city", "2", "area", "2", "max", "choice"];

const filtered = arr.filter(item => !isNaN(item));

console.log(filtered);

answered Jun 19, 2019 at 14:28

user4676340

1 Comment

user4676340 Over a year ago

Why the downvote though, that's a totally valid answer. Have the decency to explain your actions when you do them ...

Hien Nguyen · Accepted Answer · 2019-06-19 14:28:53Z

0

You can use filter method with isNaN function var numbers = arr.filter(c=> !isNaN(c));

var arr = ["abc", "5", "city", "2", "area", "2", "max", "choice"];
var numbers = arr.filter(c=> !isNaN(c));
console.log(numbers);

answered Jun 19, 2019 at 14:28

Hien Nguyen

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Comments

ellipsis · Accepted Answer · 2019-06-19 14:44:50Z

0

Using forEach loops and checking using isNaN()

var arr = ["abc", "5", "city", "2", "area", "2", "max"];
var a=[];
arr.forEach(e=>isNaN(e)?true:a.push(e))
console.log(a)

edited Jun 19, 2019 at 14:44

answered Jun 19, 2019 at 14:33

ellipsis

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1 Comment

VLAZ Over a year ago

isNaN(Number(e)) - converting using Number is redundant. isNaN is already enough. It's badly named - it's actually isArgumentGoingToConvertToNaNWhenYouConvertItToNumber

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