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join

JS TODO

Joins all elements of an array into a string and returns this string. Uses a separator and an end separator.

Use Array.prototype.reduce() to combine elements into a string. Omit the second argument, separator, to use a default separator of ','. Omit the third argument, end, to use the same value as separator by default.

const join = (arr, separator = ",", end = separator) =>
arr.reduce(
(acc, val, i) =>
i === arr.length - 2
? acc + val + end
: i === arr.length - 1
? acc + val
: acc + val + separator,
""
);
join(["pen", "pineapple", "apple", "pen"], ",", "&"); // "pen,pineapple,apple&pen"
join(["pen", "pineapple", "apple", "pen"], ","); // "pen,pineapple,apple,pen"
join(["pen", "pineapple", "apple", "pen"]); // "pen,pineapple,apple,pen"