Array to Comma separated string and for last tag use the 'and' instead of comma in jquery

Question

I have checked many questions and answers regarding join array with comma separated string, But my problem is that, I am making the string readable for human i.e I have tag

Answer 1

Another quick solution is to replace the last comma with and.

The following code:

var a = [0,1,2,3,4];
a.join(', ').replace(/,(?!.*,)/gmi, ' and');

should do the trick. (Also, play with the regex modifiers to your need).

One probable issue might be of time when you have large array, but it should work.

Answer 2

(note: you may skip to the end to find the final ready-to-pick code)

The one-liner from Blender's answer works great, though I'd favor something more understandable:

function arrayToText(a) {
    if (a.length === 0) {
        return '';
    } else if (a.length === 1) {
        return String(a[0]); // cast to string, for consistency with the other cases
    } else if (a.length === 2) {
        return a.join(' and ');
    } else {
        return a.slice(0, -1).join(', ') + ' and ' + a[a.length-1];
    }
}

The same using a switch, see how nicer it is to read:

function arrayToText(a) {
    switch (a.length) {
        case 0:
            return '';
        case 1:
            return String(a[0]); // cast to string, for consistency with the other cases
        case 2:
            return a.join(' and ');
        default:
            return a.slice(0, -1).join(', ') + ' and ' + a[a.length-1];
    }
}

Of course, these codes can be shortened/optimized, for example by merging the "0", "1" and "2" cases into just the a.join(' and ') from the case "2". I let you tweak these codes according to your taste :)

Finally, here is my end result, I think it has a great balance between understandability, shortness and efficiency:

function arrayToText(a) {
    if (a.length <= 2) {
        return a.join(' and ');
    } else {
        return a.slice(0, -1).join(', ') + ' and ' + a[a.length-1];
    }
}

Answer 3

1. Create comma separated string
2. Reverse it
3. Replace first occurrence of " ," with " dna " (" and " backwards)
4. Reverse it again

[1, 2, 3]
    .join(', ')
    .split('').reverse().join('')
    .replace(' ,', ' dna ')
    .split('').reverse().join('')

Answer 4

Able to solve it using reduce as well:

let items = [1, 2, 3, 4, 5];
items.reduce((acc, curr, i) =>
    i !== 0 ? acc + `${items.length - 1 === i ? ` and  ` : ', '}` + curr : curr, '');
// "1, 2, 3, 4 and  5"

Answer 5

Try this:

    var substr = new Array("One", "Two", "Three");
    var commaList = '';

    var i;
    for (i = 0; i < substr.length; ++i) {
        if (i == substr.length - 1)
            commaList += " and " + substr[i];
        else
            commaList += ", " + substr[i];
    }

    console.debug(commaList.substr(2, commaList.length));

Answer 6

You can use .slice():

> var a = [1, 2, 3, 4, 5];
> [a.slice(0, -1).join(', '), a.slice(-1)[0]].join(a.length < 2 ? '' : ' and ');
'1, 2, 3, 4 and 5'

• a.slice(0, -1).join(', '): takes all but the last element and joins them together with a comma.
• a.slice(-1)[0]: it's the last element.
• .join(a.length < 2 ? '' : ' and '): joins that string and the last element with and if there are at least two elements.