includes.js (1772B)
1 var baseIndexOf = require('./_baseIndexOf'), 2 isArrayLike = require('./isArrayLike'), 3 isString = require('./isString'), 4 toInteger = require('./toInteger'), 5 values = require('./values'); 6 7 /* Built-in method references for those with the same name as other `lodash` methods. */ 8 var nativeMax = Math.max; 9 10 /** 11 * Checks if `value` is in `collection`. If `collection` is a string, it's 12 * checked for a substring of `value`, otherwise 13 * [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) 14 * is used for equality comparisons. If `fromIndex` is negative, it's used as 15 * the offset from the end of `collection`. 16 * 17 * @static 18 * @memberOf _ 19 * @since 0.1.0 20 * @category Collection 21 * @param {Array|Object|string} collection The collection to inspect. 22 * @param {*} value The value to search for. 23 * @param {number} [fromIndex=0] The index to search from. 24 * @param- {Object} [guard] Enables use as an iteratee for methods like `_.reduce`. 25 * @returns {boolean} Returns `true` if `value` is found, else `false`. 26 * @example 27 * 28 * _.includes([1, 2, 3], 1); 29 * // => true 30 * 31 * _.includes([1, 2, 3], 1, 2); 32 * // => false 33 * 34 * _.includes({ 'a': 1, 'b': 2 }, 1); 35 * // => true 36 * 37 * _.includes('abcd', 'bc'); 38 * // => true 39 */ 40 function includes(collection, value, fromIndex, guard) { 41 collection = isArrayLike(collection) ? collection : values(collection); 42 fromIndex = (fromIndex && !guard) ? toInteger(fromIndex) : 0; 43 44 var length = collection.length; 45 if (fromIndex < 0) { 46 fromIndex = nativeMax(length + fromIndex, 0); 47 } 48 return isString(collection) 49 ? (fromIndex <= length && collection.indexOf(value, fromIndex) > -1) 50 : (!!length && baseIndexOf(collection, value, fromIndex) > -1); 51 } 52 53 module.exports = includes;