26 lines
804 B
Markdown
26 lines
804 B
Markdown
---
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title: Map string
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tags: string
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cover: budapest-palace
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firstSeen: 2018-07-14T10:59:56+03:00
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lastUpdated: 2020-10-21T21:54:53+03:00
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---
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Creates a new string with the results of calling a provided function on every character in the given string.
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- Use `String.prototype.split()` and `Array.prototype.map()` to call the provided function, `fn`, for each character in `str`.
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- Use `Array.prototype.join()` to recombine the array of characters into a string.
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- The callback function, `fn`, takes three arguments (the current character, the index of the current character and the string `mapString` was called upon).
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```js
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const mapString = (str, fn) =>
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str
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.split('')
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.map((c, i) => fn(c, i, str))
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.join('');
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```
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```js
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mapString('lorem ipsum', c => c.toUpperCase()); // 'LOREM IPSUM'
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```
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