mirror of
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71 lines
2.2 KiB
JavaScript
71 lines
2.2 KiB
JavaScript
/**
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* lodash 3.0.1 (Custom Build) <https://lodash.com/>
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* Build: `lodash modern modularize exports="npm" -o ./`
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* Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
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* Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
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* Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
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* Available under MIT license <https://lodash.com/license>
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*/
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/**
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* Used as the [maximum length](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-number.max_safe_integer)
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* of an array-like value.
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*/
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var MAX_SAFE_INTEGER = Math.pow(2, 53) - 1;
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/**
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* The base implementation of `_.at` without support for string collections
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* and individual key arguments.
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*
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* @private
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* @param {Array|Object} collection The collection to iterate over.
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* @param {number[]|string[]} props The property names or indexes of elements to pick.
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* @returns {Array} Returns the new array of picked elements.
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*/
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function baseAt(collection, props) {
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var index = -1,
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length = collection.length,
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isArr = isLength(length),
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propsLength = props.length,
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result = Array(propsLength);
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while(++index < propsLength) {
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var key = props[index];
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if (isArr) {
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result[index] = isIndex(key, length) ? collection[key] : undefined;
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} else {
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result[index] = collection[key];
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}
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}
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return result;
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}
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/**
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* Checks if `value` is a valid array-like index.
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*
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* @private
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* @param {*} value The value to check.
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* @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
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* @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
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*/
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function isIndex(value, length) {
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value = +value;
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length = length == null ? MAX_SAFE_INTEGER : length;
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return value > -1 && value % 1 == 0 && value < length;
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}
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/**
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* Checks if `value` is a valid array-like length.
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*
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* **Note:** This function is based on [`ToLength`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength).
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*
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* @private
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* @param {*} value The value to check.
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* @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
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*/
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function isLength(value) {
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return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
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}
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module.exports = baseAt;
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