Joining strings except empty ones in javascript

Question

I was wondering what is the best way to join a few strings in javascript except if they are empty.

Say we have

let s1 = 'X = 1';
let s2 = '';
let s3 = 'Z = 3';

And my end result need to be "X = 1, Z = 3"

let str = [s1,s2,s3].join(',')  // will have extra comma

let str = [s1!??' , ' ,s2!??' , ' ,s3].join(' ')  //is ugly, and will not work

let str = [u1&&',' ,u2&&',',u3].join('')  //close, but no cigar.

But I am sure there must be an elegant way to do this join!

And someone here on stackoverflow will point me in the right direction.

Use .filter() to create a new array without empty strings, and then .join() that. — Pointy
– Pointy, Commented Feb 24, 2022 at 14:55
Thanks.let str = [u1,u2,u3].filter(e => e.length).join(','); works 100%. — Clothahump
– Clothahump, Commented Feb 24, 2022 at 15:13
.filter(Boolean) will also work since an empty string is falsey value. Also, comma is default delimiter for .join() if you really wanna code golf it. — CrayonViolent
– CrayonViolent, Commented Feb 24, 2022 at 20:11
@Clothahump I added an answer. Did you get a chance to look into that. Hope it will work as per your expectation. — Rohìt Jíndal
– Rohìt Jíndal, Commented Mar 1, 2022 at 5:58

Rohìt Jíndal · Accepted Answer · 2022-02-26 14:55:33Z

5

You can use .filter(Boolean) (which is the same as .filter(x => x)) removes all falsy values (null, undefined, empty strings etc...)

Working Demo :

let s1 = 'X = 1';
let s2 = '';
let s3 = 'Z = 3';

let str = [s1,s2,s3].filter(Boolean).join(", ");

console.log(str);

answered Feb 26, 2022 at 14:55

Rohìt Jíndal

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Comments

dennohpeter · Accepted Answer · 2022-02-28 17:37:00Z

0

You can also achieve the same using the code below. Filter Boolean eliminates all falsey values like undefined, empty strings, null etc

  let str = [u1,u2,u3].filter(Boolean).join(',');

edited Feb 28, 2022 at 17:37

answered Feb 24, 2022 at 20:11

dennohpeter

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1 Comment

MadSkunk Over a year ago

Some comments describing this would be helpful.

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