8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
28 lines
843 B
Markdown
28 lines
843 B
Markdown
### join
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Joins all elements of an array into a string and returns this string.
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Uses a separator and an end separator.
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Use `Array.prototype.reduce()` to combine elements into a string.
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Omit the second argument, `separator`, to use a default separator of `','`.
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Omit the third argument, `end`, to use the same value as `separator` by default.
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```js
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const join = (arr, separator = ',', end = separator) =>
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arr.reduce(
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(acc, val, i) =>
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i === arr.length - 2
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? acc + val + end
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: i === arr.length - 1
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? acc + val
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: acc + val + separator,
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''
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);
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```
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```js
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join(['pen', 'pineapple', 'apple', 'pen'], ',', '&'); // "pen,pineapple,apple&pen"
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join(['pen', 'pineapple', 'apple', 'pen'], ','); // "pen,pineapple,apple,pen"
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join(['pen', 'pineapple', 'apple', 'pen']); // "pen,pineapple,apple,pen"
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```
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