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36 lines
1.2 KiB
JavaScript
36 lines
1.2 KiB
JavaScript
import baseAssignValue from './.internal/baseAssignValue.js'
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import reduce from './reduce.js'
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/** Used to check objects for own properties. */
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const hasOwnProperty = Object.prototype.hasOwnProperty
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/**
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* Creates an object composed of keys generated from the results of running
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* each element of `collection` thru `iteratee`. The order of grouped values
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* is determined by the order they occur in `collection`. The corresponding
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* value of each key is an array of elements responsible for generating the
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* key. The iteratee is invoked with one argument: (value).
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*
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* @since 0.1.0
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* @category Collection
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* @param {Array|Object} collection The collection to iterate over.
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* @param {Function} iteratee The iteratee to transform keys.
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* @returns {Object} Returns the composed aggregate object.
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* @example
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*
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* groupBy([6.1, 4.2, 6.3], Math.floor)
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* // => { '4': [4.2], '6': [6.1, 6.3] }
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*/
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function groupBy(collection, iteratee) {
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return reduce(collection, (result, value, key) => {
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if (hasOwnProperty.call(result, key)) {
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result[key].push(value)
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} else {
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baseAssignValue(result, key, [value])
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}
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return result
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}, {})
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}
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export default groupBy
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