31 lines
879 B
Markdown
31 lines
879 B
Markdown
---
|
|
title: join
|
|
tags: array,intermediate
|
|
---
|
|
|
|
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.
|
|
|
|
```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(['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"
|
|
``` |