26 lines
620 B
Markdown
26 lines
620 B
Markdown
---
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title: Reverse compose functions
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type: snippet
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language: javascript
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tags: [function]
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cover: rocky-beach
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dateModified: 2020-10-22T20:23:47+03:00
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---
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Performs left-to-right function composition.
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- Use `Array.prototype.reduce()` to perform left-to-right function composition.
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- The first (leftmost) function can accept one or more arguments; the remaining functions must be unary.
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```js
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const composeRight = (...fns) =>
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fns.reduce((f, g) => (...args) => g(f(...args)));
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```
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```js
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const add = (x, y) => x + y;
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const square = x => x * x;
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const addAndSquare = composeRight(add, square);
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addAndSquare(1, 2); // 9
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```
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