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54 lines
1.9 KiB
JavaScript
54 lines
1.9 KiB
JavaScript
var createAggregator = require('../internal/createAggregator');
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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` through `iteratee`. The corresponding value
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* of each key is the last element responsible for generating the key. The
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* iteratee function is bound to `thisArg` and invoked with three arguments:
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* (value, index|key, collection).
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*
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* If a property name is provided for `iteratee` the created `_.property`
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* style callback returns the property value of the given element.
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*
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* If a value is also provided for `thisArg` the created `_.matchesProperty`
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* style callback returns `true` for elements that have a matching property
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* value, else `false`.
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*
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* If an object is provided for `iteratee` the created `_.matches` style
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* callback returns `true` for elements that have the properties of the given
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* object, else `false`.
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*
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* @static
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* @memberOf _
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* @category Collection
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* @param {Array|Object|string} collection The collection to iterate over.
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* @param {Function|Object|string} [iteratee=_.identity] The function invoked
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* per iteration.
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* @param {*} [thisArg] The `this` binding of `iteratee`.
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* @returns {Object} Returns the composed aggregate object.
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* @example
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*
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* var keyData = [
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* { 'dir': 'left', 'code': 97 },
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* { 'dir': 'right', 'code': 100 }
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* ];
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*
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* _.indexBy(keyData, 'dir');
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* // => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
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*
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* _.indexBy(keyData, function(object) {
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* return String.fromCharCode(object.code);
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* });
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* // => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
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*
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* _.indexBy(keyData, function(object) {
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* return this.fromCharCode(object.code);
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* }, String);
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* // => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
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*/
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var indexBy = createAggregator(function(result, value, key) {
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result[key] = value;
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});
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module.exports = indexBy;
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