lodash (underscore) - know your standard library

Knowledgeable people recommend that developers periodically run over their standard library in order to better present its capabilities. Why once again reinvent the wheel, when we have already done so much, and, most importantly, are well tested, and sometimes even normally documented. It is said that the full use of the standard library greatly improves performance.



Well, lately, in my work I will use lodash in all projects (someone might like underscore more ). For me, this is actually a standard. Once again, running through the eyes of the API, I decided to compose a cheat sheet for myself in the form: “function name” - “short description”. It is so convenient to refresh the API in memory. Maybe someone will come in handy.

Arrays

compact	Remove from the array all empty elements (0, "", null , undefined )
difference	We create a new array, as the difference, where all values ​​of the second ( A - B ) were excluded from the first array
findIndex	Returns the index of the first element by which callback returns true
findLastIndex	Returns the index of the first since the end of the element, on which callback returned true
first	Returns the first or several first elements of an array
flatten	Extracts, in the form of an array, elements from the objects contained in the transmitted array
indexOf	Returns the index of the first matching (===) element, if the array is sorted, you can speed up the search
initial	Returns the initial part of the array (except the last n)
intersection	Returns the intersection of arrays (several)
last	Returns the last or several last elements of an array
lastIndexOf	Returns the index of the last matching (===) element. (you can not search from the very end)
pull	Removes the passed elements from the array.
range	Creates an array with numbers from start to end (you can select a step)
remove	Removes elements from an array according to the specified rule and returns an array of deleted elements.
rest	Returns everything except the first (first few) array elements.
sortedIndex	Returns the insert index of the current value in a sorted array.
union	Returns an array of unique values ​​- the result of combining several arrays
uniq	Creates a copy of the array without duplicates.
without	Creates a new array from the existing one, excluding some values.
xor	Creates a new array - “semantic difference” between the transferred arrays
zip	Creates an array of elements grouped into subarrays. At the input accepts several arrays. Assembles as follows: the first elements of all input arrays fall into the first group, etc.
zipObject	Collects an object from two arrays (with keys and with values)

Collections

at	Creates a new collection, only from the listed items.
contains	Checks whether a particular item is contained in the collection.
countBy	Creates an object whose keys are the values ​​returned by the callback function, and the values ​​are the number of corresponding returns.
every	Check that all elements of the collection are true (or satisfy the condition).
filter	Runs through all the elements of the collection and returns the MASSIF of the elements that satisfy the condition
find	Returns the first element of the collection that meets the specified criteria.
findLast	Same as find , only from the end
forEach	Runs through all elements of the collection by invoking a callback function for each element.
forEachRight	The same as forEach, only from the end
groupBy	Creates a collection whose keys are the values ​​returned by the callback function, and the values ​​are arrays from the original elements of the collection
indexBy	Creates a collection, the keys of which are the values ​​returned by the callback function, and the values ​​are the last elements of the original collection with the corresponding key
invoke	Executes a specific method for each item in the collection and returns an array of the results of this execution.
map	Creates an array of elements, driving each element of the collection through a callback function.
max	Returns the maximum value of the collection.
min	Returns the minimum value of the collection.
pluck	Returns all the values ​​of a specific collection property.
reduce	Reduce the collection to the value received by calling the callback functions for each value. In addition to the value itself, the result of the previous call is also transferred to this function.
reduceRight	Same as reduce , only from the end
reject	In contrast to filter , this function returns an array of collection elements that do not satisfy the condition.
sample	Returns a random collection item.
shuffle	Returns an array of randomly shuffled elements of the collection.
size	Returns the size of the collection.
some	Check that at least one element of the collection is true (or satisfies the condition).
sortBy	Returns an array of sorted in ascending collection items. For sorting, the values ​​obtained by the callback function for each element are used.
toArray	Converts a collection to an array. Useful for working with arguments.
where	Conducts a deep comparison of each element with a specific object. Returns an array that satisfies the comparison.

Functions

after	Returns the function that will call the transferred callback only after the nth call
bind	Returns the function that, when invoked, will be bound to the current this , to the bound arguments and arguments that are passed to the function itself.
bindAll	Binds all object methods to this object itself ( this object will always contain the object itself)
bindKey	Binds an object method to the object itself (at the time of binding, the method may not yet exist)
compose	Returns a function - a composition of the passed functions. Pass f, g, h - returns the function = f (g (h ()))
curry	Accepts a function with n parameters as input, and returns a function that, if the parameter is sufficient, will call the input function, if not, return another function, passing the remaining parameters of which will call the original one.
debounce	Returns a function that will start the input function only after a pause after its last run. (elimination of rattling)
defer	Calls the input function when the current call stack is released (at the beginning of the next event cycle)
delay	Call the input function after n milliseconds.
memoize	Returns a function that caches the results of its execution, and is not executed if the result is in the cache.
once	Returns a function that will call the input only once. In subsequent times, the result will be returned.
partial	Same as bind , but does not bind this
partialRight	Same as partial , but binds to parameters on the right.
throttle	Returns a function that calls the original no more than once every n milliseconds
wrap	Creates a function in the first parameter of which the first parameter of the wrapper will be passed.

Objects

assign	Supplements an object with missing (not just undefined ) properties from another object.
clone	Makes a copy of an object (nested objects are copied by reference)
cloneDeep	Deep object copying (nested objects are copied by content)
create	Creates an object by its prototype and properties.
defaults	Supplements an object with missing (=== undefined ) properties from another object — sets defaults
findKey	Searches for the first object that satisfies the conditions - returns the key
findLastKey	Searches for the last object satisfying the conditions - returns the key
forIn	Bypasses all object properties (including internal) by calling a callback function for each of them.
forInRight	Same as forIn only from the end
forOwn	Wraps all the object's own properties by calling a callback function for each of them.
forOwnRight	Same as forOwn only from the end.
functions	Returns a sorted array of names of all the properties of an object whose values ​​are functions.
has	Checks whether the specified property is an object's own property.
invert	Creates an object whose keys and values ​​are swapped
isArguments	Checks whether a value is an object of arguments
isArray	Checks if a value is an array
isBoolean	Checks whether the value is a boolean variable
isDate	Checks if a value is an array
isElement	Checks if a DOM value is an element
isEmpty	Checks if a value is empty. Arrays, strings, arguments - objects with zero length are considered empty
isEqual	Conducts a deep comparison of two values.
isFinite	Checks whether a given value is a finite number, or it can be converted to it.
isFunction	Checks if a given value is a function
isNaN	Checks the value for === NaN (this is not the same as the standard isNuN , which returns true for undefined and not numeric values)
isNull	Checks value for === null
isNumber	Checks whether a value is a number ( NaN is also considered a number)
isObject	Checks if a value is an object
isPlainObject	Checks whether a value is a pure object (created by the Object constructor)
isRegExp	Checks if the value is a regular expression
isString	Checks if a value is a string
isUndefined	Checks value to === undefined
keys	Returns an array of object keys
mapValues	Creates a new object with the same keys as the original, the values ​​are obtained by calling the callback function to each element.
merge	Recursively adds transferred objects to the destination.
omit	Returns an object that has some properties removed.
pairs	Creates a two-dimensional array from the object, of type [[key1, value1], [key2, value2]] .
pick	Creates another object from an object with properties from the list
transform	A simpler alternative to reduce - allows you to transform an incoming object into another, through a callback function, to which, in addition to the elements, the resulting object is also passed
values	Returns an array of object values.

Utilities

now	Returns the current Unix-time in milliseconds
constant	Creates a function that returns the passed value.
createCallback	Creates a function, callback - used for internal purposes. Lodash
escape	Escapes the characters &, <,>, ", and 'corresponding html entities
identity	The function returns the first argument passed to it.
mixin	Adds to the object (or lodash itself) the elements of a devotional object. If the receiving object is a function, it adds properties to the prototype.
noConflict	Makes _ equal to the old value (before running lodash ), and returns a pointer to lodash
noop	Empty function. Returns undefined
parseInt	Extracts a number from a string, by default it always works with the 10th number system (as opposed to the standard one)
property	Returns a function in the pluck style, which, when called with an object as a parameter, returns the value of a specific property.
random	Returns a random number from the range. Maybe fractional.
result	Returns the value of the property in the object (if the value is a function, it will be called and its result returned)
runInContext	Will return a new lodash function bound to the specified context.
template	Micromastering machine
times	Performs the specified callback n-time, returning an array of results
unescape	Inverse escape function
uniqueId	Returns a unique numeric ID (a number, each time one more. You can send a prefix)

PS I, of course, did not use all 100% of the functions in my work, so inaccuracies are possible - write in a personal, I will correct everything. About spelling - there too.