boxed-out

Small utility library wrapping plain Array or Object to extend with each, map, filter, reduce using indeterminate ordering, left to right, right to left that operate on own properties of array or object.

To simulate break return BREAK or RETURN, to simulate return return BREAK(value) or RETURN(value) both are equivalent but the one communicating the right intent should be used.

boxOut(array|object)

const boxOut = require('boxed-immutable').boxOut;
const boxedOut = boxOut(arg);

Used to construct a boxed-out object or array that has the extra prototype functions for iterating over own properties. Does not provide immutability or modification tracking, only prototype convenience functions. This adds ability to use the same functions on regular objects and arrays. It also enables using filter, map, reduce, etc to be used on Object properties and on Array properties, not just integer indexed properties.

argument	default	Description
arg	none	object or array to enhance with boxed-out proxy methods

Functions available on boxed-out argument:

Method	Object Arg	Array Arg	Description
filteredProps	yes	yes	property extraction to new object/array using filter value, array, object or function, this is copyFiltered applied to a new instance with this as the source
filterProps	yes	yes	.filter equivalent for objects, takes same argument: callback(value,key,object) and thisArg
mappedProps	yes	yes	object property value mapping, similar to map for arrays except builds object with original property name and mapped value
mapProps	yes	yes	builds an array of values returned from callback applied to array/object properties, order of property iteration given by each
copyFiltered	yes	yes	copying of selected properties, filter provides inclusion predicate
copyFilteredNot	yes	yes	copying of not selected properties. ie. filter provides exclusion predicate
eachProp	yes	yes	forEach like for object and array properties. Order of property iteration not guaranteed.
each	yes	yes	forEach like for objects with Array index type properties iterated first (in increasing order) then non-indexed properties sorted by sort()
eachRight	yes	yes	each but properties iterated in reverse order
cloneArrayObject	yes	yes	shallow copy array/object, but array's non-indexed properties are also copied
deleteItems	no	yes	delete array simple (not object or array, etc) items by value, given in array or object properties
arrayLength	yes	yes	equivalent to array length property for objects. Will find the maximum array index property of an object, for arrays it is just length
deepClone	yes	yes	deepClone array/object, with argument for number of levels
mergeDefaults	yes	yes	mergeDefaults, with options for levels, whether current object is immutable and whether to deepClone source when copying its values
someProps	yes	yes	some equivalent for object properties
everyProp	yes	yes	every equivalent for object properties
reduceProps	yes	yes	reduce equivalent for object properties, order of iteration not guaranteed, same as eachProp
reducePropsLeft	yes	yes	reduce equivalent with order given by each
reducePropsRight	yes	yes	reduceRight equivalent for object properties
hasOwnProperties	yes	yes	returns true if object array has own properties, optionally takes an argument for properties to be ignored
filter	synonym for filterProps	Array.prototype.filter	corresponding method for object properties
map	synonym for mapProps	Array.prototype.map	corresponding method for object properties
forEach	synonym for each	Array.prototype.forEach	corresponding method for object properties
some	synonym for someProps	Array.prototype.some	corresponding method for object properties
every	synonym for everyProp	Array.prototype.every	corresponding method for object properties
reduce	synonym for reducePropsLeft	Array.prototype.reduce	corresponding method for object properties
reduceRight	synonym for reducePropsRight	Array.prototype.reduceRight	corresponding method for object properties

Iteration over properties

The iteration functions all implement a mechanism for the callback function to break out of the loop similar to how it can be done in a regular loop. Lambda iteration is a PITA for some applications without the ability to cut the iteration short.

To break out of an iteration the callback can return BREAK a value defined in the boxedImmutable.util library. eachProp, each and eachRight also have a mechanism to return a value which the callback can set by returning BREAK(arg). With these two mechanisms it is possible to break out of an iteration and have these iterators return a value the same way it can be done in regular looping constructs.

To prepare a default return value before invoking a callback which can potentially use the simple BREAK return value, you can use BREAK.setDefault(arg), returning BREAK will then be equivalent to returning BREAK(arg).

Some iterators define the default value that will be returned if a callback BREAKs our of a loop or ignore the value returned through BREAK where their return value is determined by their operation.

Install

Use npm to install.

npm install boxed-out --save

Usage

License

MIT, see LICENSE.md for details.