How can I regex this array/string?

Question

array = ['item1', 'item2', 'item3', 'item4']
output = array.toString()

This gets me "item1,item2,item3,item4" but I need to turn this into "item1, item2, item3, and item4" with spaces and "and"

How could I construct a regex process to do this rather then substringing and find/replacing?

Is this the best way?

Thanks!

jmar777 · Accepted Answer · 2012-05-17 17:51:03Z

4

Try this:

var array = ['item1', 'item2', 'item3', 'item4'];
array.push('and ' + array.pop());
var output = array.join(', ');
// output = 'item1, item2, item3, and item4'

Edit: if you really do want a regex-based solution:

var output = array.join(',')
    .replace(/([^,]+),/g, '$1, ').replace(/, ([^,]+)$/, ' and $1');

Another edit:

Here's another non-regex approach that doesn't mess with the original array variable:

var output = array.slice(0,-1).concat('and ' + array.slice(-1)).join(', ');

edited May 17, 2012 at 17:51

answered May 17, 2012 at 17:42

jmar777

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4 Comments

HBP Over a year ago

But it does change the array which might cause problems downstream. Also does not quite work for arrays of length 1.

jmar777 Over a year ago

I guess if that's a problem you can just do array2 = array.slice();

jmar777 Over a year ago

Good point though - I should have mentioned that my approach isn't side-effect free.

jmar777 Over a year ago

Added two alternative approaches - one with regular expressions, and another one that does array manip, but leaves array intact.

HBP · Accepted Answer · 2012-05-17 18:21:57Z

1

This version handles all the variations I could think of :

function makeList (a) {
  if (a.length < 2)
    return a[0] || '';

  if (a.length === 2)
    return a[0] + ' and ' + a[1];

  return a.slice (0, -1).join (', ') + ', and '  + a.slice (-1);
}    

console.log ([makeList ([]), 
              makeList (['One']), 
              makeList (['One', 'Two']), 
              makeList(['One', 'Two', 'Three']),
              makeList(['One', 'Two', 'Three', 'Four'])]);

// Displays : ["", "One", "One and Two", "One, Two, and Three", "One, Two, Three, and Four"]

answered May 17, 2012 at 18:21

HBP

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Comments

Elliot Bonneville · Accepted Answer · 2012-05-17 17:39:50Z

0

var output = array.join(", ");
output = outsput.substr(0, output.lastIndexOf(", ") + " and " + output.substr(output.lastIndexOf(" and "));

answered May 17, 2012 at 17:39

Elliot Bonneville

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