Javascript function accepts both arrays and strings as parameter

Question

I have this code:

    var showRegion = function(key) {
        if (key in regionOptions) {
            var entry       = regionOptions[key];
            var builder     = entry.builder;
            var layoutObj   = entry.layoutObj;
            var viewStarter = entry.viewStarter;

            var view = new builder();
            logger.info('Controller.' + key + ' => CreateAccountLayoutController');
            Controller.layout[layoutObj].show(view);
            view[viewStarter]();
        }
    };

What I need is that the parameter should be able to accept an array or a string, and should work either way.

Sample function calls:

showRegion('phoneNumberRegion');
showRegion(['phoneNumberRegion', 'keyboardRegion', 'nextRegion']);

i thinks its better to use === instead of == or so i have readed — Juan Antonio Orozco
– Juan Antonio Orozco, Commented May 20, 2013 at 3:35
@JuanAntonioOrozco typeof always returns a string, and I'm comparing it to a string. === is superfluous, since the types are guaranteed to match already. — Niet the Dark Absol
– Niet the Dark Absol, Commented May 20, 2013 at 3:36

Cohars · Accepted Answer · 2018-03-16 08:48:05Z

20

This post is old, but here is a pretty good tip:

function showRegions(keys) {
  keys = [].concat(keys)
  return keys
}

// short way
const showRegions = key => [].concat(keys)

showRegions(1) // [1]
showRegions([1, 2, 3]) // [1, 2, 3]

edited Mar 16, 2018 at 8:48

answered Jul 10, 2016 at 1:24

Cohars

4,0501 gold badge34 silver badges51 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

gduq Over a year ago

Same idea as the accepted answer but more elegant. Thanks!

Havenard · Accepted Answer · 2013-05-20 03:36:05Z

9

var showRegion = function(key) {
    if (typeof key === 'string')
         key = [key];
    if (key in regionOptions) {
       ...

No need to make a code for each case, just convert key string into an array of one element and the code for arrays will do for both.

answered May 20, 2013 at 3:36

Havenard

28.1k5 gold badges38 silver badges66 bronze badges

1 Comment

Raymond Chen Over a year ago

Well except that the original code handled only strings, so now you converted something that works into something that doesn't. But presumably the OP can take your idea and make it work.

Sudhir Bastakoti · Accepted Answer · 2013-05-20 03:37:31Z

0

you could use typeof to check for the type of your argument and proceed accordingly, like

var showRegion = function(key) {
  if( typeof key === 'object') {
      //its an object
  }
  else {
     //not object
  }
}

answered May 20, 2013 at 3:37

Sudhir Bastakoti

100k15 gold badges163 silver badges169 bronze badges

Comments

storsoc · Accepted Answer · 2016-12-15 19:25:02Z

You can use the fact that string.toString() always returns the same string and Array.toString() returns a comma-delimited string in combination with string.split(',') to accept three possible inputs: a string, an array, a comma-delimited string -- and reliably convert to an array (provided that you're not expecting commas to be part of the values themselves, and you don't mind numbers becoming strings).

In the simplest sense:

x.toString().split(',');

So that

'a' -> ['a']
['a','b'] -> ['a','b']
'a,b,c' -> ['a','b','c']
1 -> ['1']

Ideally, you may want to tolerate null, undefined, empty-string, empty-array (and still keep a convenient one-liner):

( (x || x === 0 ) && ( x.length || x === parseFloat(x) ) ? x.toString().split(',') : []);

So that also

null|undefined -> []
0 -> ['0']
[] -> []
'' -> []

You may want to interpret null/empty/undefined differently, but for consistency, this method converts those to an empty array, so that downstream code does not have to check beyond array-having-elements (or if iterating, no check necessary.)

This may not be terribly performant, if that's a constraint for you.

In your usage:

var showRegion = function(key) {
    key = ( (key || key === 0 ) && ( key.length || key === parseFloat(key) ) ? key.toString().split(',') : []);

    /* do work assuming key is an array of strings, or an empty array */
}

Collectives™ on Stack Overflow

Javascript function accepts both arrays and strings as parameter

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related