1 | var baseFindIndex = require('./_baseFindIndex'),
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2 | baseIteratee = require('./_baseIteratee'),
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3 | toInteger = require('./toInteger');
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4 |
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5 | /* Built-in method references for those with the same name as other `lodash` methods. */
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6 | var nativeMax = Math.max;
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7 |
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8 | /**
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9 | * This method is like `_.find` except that it returns the index of the first
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10 | * element `predicate` returns truthy for instead of the element itself.
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11 | *
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12 | * @static
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13 | * @memberOf _
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14 | * @since 1.1.0
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15 | * @category Array
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16 | * @param {Array} array The array to inspect.
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17 | * @param {Function} [predicate=_.identity] The function invoked per iteration.
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18 | * @param {number} [fromIndex=0] The index to search from.
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19 | * @returns {number} Returns the index of the found element, else `-1`.
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20 | * @example
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21 | *
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22 | * var users = [
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23 | * { 'user': 'barney', 'active': false },
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24 | * { 'user': 'fred', 'active': false },
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25 | * { 'user': 'pebbles', 'active': true }
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26 | * ];
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27 | *
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28 | * _.findIndex(users, function(o) { return o.user == 'barney'; });
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29 | * // => 0
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30 | *
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31 | * // The `_.matches` iteratee shorthand.
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32 | * _.findIndex(users, { 'user': 'fred', 'active': false });
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33 | * // => 1
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34 | *
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35 | * // The `_.matchesProperty` iteratee shorthand.
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36 | * _.findIndex(users, ['active', false]);
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37 | * // => 0
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38 | *
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39 | * // The `_.property` iteratee shorthand.
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40 | * _.findIndex(users, 'active');
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41 | * // => 2
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42 | */
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43 | function findIndex(array, predicate, fromIndex) {
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44 | var length = array == null ? 0 : array.length;
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45 | if (!length) {
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46 | return -1;
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47 | }
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48 | var index = fromIndex == null ? 0 : toInteger(fromIndex);
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49 | if (index < 0) {
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50 | index = nativeMax(length + index, 0);
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51 | }
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52 | return baseFindIndex(array, baseIteratee(predicate, 3), index);
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53 | }
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54 |
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55 | module.exports = findIndex;
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