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30-seconds-of-code/snippets/join.md
2018-01-01 12:38:25 +00:00

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### join
Joins all elements of an array into a string and returns this string. Uses a separator and an end separator.
Use `Array.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.
```js
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,
''
);
```
```js
join(); // ''
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"
```