18 lines
523 B
Markdown
18 lines
523 B
Markdown
### transform
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Applies a function against an accumulator and each key in the object (from left to right).
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Use `Object.keys(obj)` to iterate over each key in the object, `Array.reduce()` to call the apply the specified function against the given accumulator.
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```js
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const transform = (obj, fn, acc) =>
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Object.keys(obj).reduce((a, k) => fn(a, obj[k], k, obj), acc);
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```
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```js
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transform({ 'a': 1, 'b': 2, 'c': 1 }, (r, v, k) => {
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(r[v] || (r[v] = [])).push(k);
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return r;
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}, {}); // { '1': ['a', 'c'], '2': ['b'] }
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```
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