30 lines
824 B
JavaScript
30 lines
824 B
JavaScript
/**
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* Creates a keyed JS object from an array, given a function to produce the keys
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* for each value in the array.
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*
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* This provides a convenient lookup for the array items if the key function
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* produces unique results.
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*
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* const phoneBook = [
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* { name: 'Jon', num: '555-1234' },
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* { name: 'Jenny', num: '867-5309' }
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* ]
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*
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* // { Jon: { name: 'Jon', num: '555-1234' },
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* // Jenny: { name: 'Jenny', num: '867-5309' } }
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* const entriesByName = keyMap(
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* phoneBook,
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* entry => entry.name
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* )
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*
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* // { name: 'Jenny', num: '857-6309' }
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* const jennyEntry = entriesByName['Jenny']
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*
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*/
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export default function keyMap(list, keyFn) {
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return list.reduce(function (map, item) {
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map[keyFn(item)] = item;
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return map;
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}, Object.create(null));
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}
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