isUndefined_.isUndefined(value) Returns true if value is undefined. _.isUndefined(window.missingVariable); => true

contains_.contains(list, value, [fromIndex]) Alias: includes Returns true if the value is present in the list. Uses indexOf internally, if list is an Array. Use fromIndex to start your search at a given index. _.contains([1, 2, 3], 3); => true

isRegExp_.isRegExp(object) Returns true if object is a RegExp. _.isRegExp(/moe/); => true

propertyOf_.propertyOf(object) Inverse of _.property. Takes an object and returns a function which will return the value of a provided property. var stooge = {name: 'moe'}; _.propertyOf(stooge)('name'); => 'moe'

random_.random(min, max) Returns a random integer between min and max, inclusive. If you only pass one argument, it will return a number between 0 and that number. _.random(0, 100); => 42

findKey_.findKey(object, predicate, [context]) Similar to _.findIndex but for keys in objects. Returns the key where the predicate truth test passes or undefined.

isNull_.isNull(object) Returns true if the value of object is null. _.isNull(null); => true _.isNull(undefined); => false

object_.object(list, [values]) Converts arrays into objects. Pass either a single list of [key, value] pairs, or a list of keys, and a list of values. If duplicate keys exist, the last value wins. _.object(['moe', 'larry', 'curly'], [30, 40, 50]); => {moe: 30, larry: 40, curly: 50} _.object([['moe', 30], ['larry', 40], ['curly', 50]]); => {moe: 30, larry: 40, curly: 50}

values_.values(object) Return all of the values of the object's own properties. _.values({one: 1, two: 2, three: 3}); => [1, 2, 3]

reduceRight_.reduceRight(list, iteratee, memo, [context]) Alias: foldr The right-associative version of reduce. Foldr is not as useful in JavaScript as it would be in a language with lazy evaluation. var list = [[0, 1], [2, 3], [4, 5]]; var flat = _.reduceRight(list, function(a, b) { return a.concat(b); }, []); => [4, 5, 2, 3, 0, 1]