StdLib Array

Array

The Array built-in provides methods for creating and manipulating JavaScript arrays.

Implementation Status: 100% Complete

Overview

Category	Methods	Implemented
Static Methods	4	4
Iterator Methods	3	3
Transformation Methods	16	16
Iteration (HOF) Methods	11	11
Mutator Methods	8	8
Total	42	42

Static Methods (Array.xxx)

Method	Status	Description
Array.isArray(value)	Implemented	Checks if value is an array
Array.of(...items)	Implemented	Creates array from arguments
Array.from(arrayLike, mapFn, thisArg)	Implemented	Creates array from iterable/array-like
Array.fromAsync(asyncIterable, mapFn, thisArg)	Implemented	Creates array from async iterable (ES2024)
Array[Symbol.species]	Implemented	Returns constructor for derived objects

Iterator Methods

Method	Status	Description
entries()	Implemented	Returns iterator of [index, value] pairs
keys()	Implemented	Returns iterator of indices
values()	Implemented	Returns iterator of values
[Symbol.iterator]	Implemented	Alias for values()

Transformation Methods

Method	Status	Description
join(separator)	Implemented	Joins elements with separator
toString()	Implemented	Calls join() or Object.prototype.toString
includes(value, fromIndex)	Implemented	SameValueZero comparison
indexOf(value, fromIndex)	Implemented	Strict equality search
lastIndexOf(value, fromIndex)	Implemented	Reverse search
toLocaleString()	Implemented	Calls element toLocaleString methods
slice(start, end)	Implemented	Returns shallow copy of portion
at(index)	Implemented	Relative indexing (ES2022)
flat(depth)	Implemented	Flattens nested arrays
flatMap(callback)	Implemented	Maps and flattens one level
fill(value, start, end)	Implemented	Fills with value
copyWithin(target, start, end)	Implemented	Copies within array
toSorted(compareFn)	Implemented	Non-mutating sort (ES2023)
toReversed()	Implemented	Non-mutating reverse (ES2023)
toSpliced(start, deleteCount, ...items)	Implemented	Non-mutating splice (ES2023)
with(index, value)	Implemented	Non-mutating element replacement (ES2023)

Iteration (Higher-Order Function) Methods

Method	Status	Description
map(callback, thisArg)	Implemented	Creates new array with results
filter(callback, thisArg)	Implemented	Creates array with matching elements
reduce(callback, initialValue)	Implemented	Reduces to single value (left-to-right)
reduceRight(callback, initialValue)	Implemented	Reduces to single value (right-to-left)
forEach(callback, thisArg)	Implemented	Executes callback for each element
find(predicate, thisArg)	Implemented	Finds first matching element
findIndex(predicate, thisArg)	Implemented	Finds index of first match
some(predicate, thisArg)	Implemented	Tests if any element matches
every(predicate, thisArg)	Implemented	Tests if all elements match
findLast(predicate, thisArg)	Implemented	Finds last matching element (ES2023)
findLastIndex(predicate, thisArg)	Implemented	Finds index of last match (ES2023)

Mutator Methods (In-Place)

Method	Status	Description
push(...items)	Implemented	Adds elements to end
pop()	Implemented	Removes last element
shift()	Implemented	Removes first element
unshift(...items)	Implemented	Adds elements to beginning
splice(start, deleteCount, ...items)	Implemented	Removes/replaces/adds elements
reverse()	Implemented	Reverses in place
concat(...items)	Implemented	Merges arrays (@@isConcatSpreadable)
sort(compareFn)	Implemented	Sorts in place (stable)

Implementation Notes

Re-entrancy Guards

All mutator methods have protection against recursive calls:

// Internal __inMethodName__ flags prevent re-entry

Species Support

Methods that create new arrays respect Symbol.species for subclass compatibility.

Hole Handling

Methods correctly distinguish between holes (empty) and undefined values.

ES2023 Change-Array-by-Copy

The toSorted, toReversed, toSpliced, and with methods return new arrays without mutating the original.

Files

File	Purpose
StdLib/Array/ArrayConstructor.cs	Static methods
StdLib/Array/ArrayPrototype.cs	Base prototype
StdLib/Array/ArrayPrototype.Transformations.cs	Transformation methods
StdLib/Array/ArrayPrototype.Iterators.cs	Iterator methods
StdLib/Array/ArrayPrototype.Iteration.cs	HOF methods
StdLib/Array/ArrayPrototype.Mutators.cs	Mutator methods

See Also

• Iterator-Protocol - How array iteration works
• StdLib-TypedArray - Typed array implementation