Turn array into comma separated grammatically correct sentence

Question

If I have an array in Javascript that looks like

searchComponents = ['element1', 'element2', 'element3'];

What is the necessary logic to turn it into a sentence like:

"element1, element2, and element3"

Likewise, if there are only two elements it should read like:

"element1 and element2"

and so on and so forth. I am stuck.

Answer 1

One easy solution:

function arrayToSentence (arr) {
    var last = arr.pop();
    return arr.join(', ') + ' and ' + last;
}

console.log(arrayToSentence(['one','two','three']));

JS Fiddle demo.

And a slightly more complex/ridiculous solution (because who doesn't like silly, occasionally...):

function arrayToSentence (arr) {
    var len = arr.length;
    return arr.reduce(function(a,b,c){
        return a + (c - 1 === length ? ', ' : ' and ') + b;
    });
}

console.log(arrayToSentence(['one','two','three']));

JS Fiddle demo.

References:

• Array.prototype.join().
• Array.prototype.pop().
• Array.prototype.reduce().

Answer 2

function toSentence(arr) {
  return arr.slice(0, -2).join(', ') + 
    (arr.slice(0, -2).length ? ', ' : '') + 
    arr.slice(-2).join(' and ');
}

usage

toSentence([1])

1

toSentence([1, 2])

1 and 2

toSentence([1, 2, 3])

1, 2 and 3

toSentence([1, 2, 3, 4, 5, 6])

1, 2, 3, 4, 5 and 6

Answer 3

Here's a one liner:

const arrayToSentence = (a) => [a.slice(0, -1).join(', '), a.pop()].filter(w => w !== '').join(' and ');

console.log(arrayToSentence(['foo', 'bar', 'baz']));
console.log(arrayToSentence(['foo', 'bar']));
console.log(arrayToSentence(['foo']));
console.log(arrayToSentence([]));