Type of elements that collection will be include
Creates new collection
const nums: Collection<number> = new Collection()
nums.push( 1 )
const vegetables = new Collection( [ {
name: 'potato',
cost: 20
}, {
name: 'squash',
cost: 31
} ] )
Items count
const vec = new Collection( [ [], [] ] )
assert( vec.length === 2 )
vec.clear()
assert( vec.length === 0 )Clears the collection, removing all values
const vec = new Collection( [ 3, 2, 1 ] )
vec.clear()
assert( vec.isEmpty() )For all elements calls a provided function to determine if an element should be removed from collection.
Works in place and returns Array of removed elements.
const nums = new Collection( [ 1, 79, 5, 42, 3 ] )
const _removed = nums.drainFilterBy( ( n ) => n > 10 )
assert( nums.length === 3 && nums.last() === 3 )
assert( _removed.length === 2 && _removed.first() === 79 )Predicate
Creates new instance of current type of collection only with elements that
pass the test implemented by the provided function.
Similar to Array.prototype.filter
const arrays = new Collection( [ [], [ 5 ], [] ] )
const nonEmptyArrays = arrays.filterBy( ( arr: number[] ): boolean => arr.length !== 0 )
assert( nonEmptyArrays.length === 1 )
assert( nonEmptyArrays.first()[ 0 ] === 5 )Predicate
Searches for an element that satisfies a predicate
Takes a closure that returns boolean. It applies this closure to each element of the collection,
and if any of them return true, then findBy() returns element. If they all return false, it returns null
const nums = new Collection( [ 1, 2, 3 ] )
const one = nums.find( ( n: number ): boolean => n === 1 )
assert( one === 1 )
const ten = nums.find( n => n === 10 )
assert( ten === null )
type Tree = { name: string }
const trees = new Collection<Tree>( [ { name: 'spruce' }, { name: 'pine' }, { name: 'poplar' } ] )
const pine = trees.find( ( t: Tree ): boolean => t.name === 'pine' )
assert( pine && pine.name === 'pine' )
const pineAtTheEnd = trees.find( t => t.name === 'pine', 2 )
assert( pine === null )Predicate
The position where to start searching
Searches for an index of element that satisfies a predicate
Like findBy but returns index
const nums = new Collection( [ 1, 2, 3 ] )
const oneInd = nums.find( ( n: number ): boolean => n === 1 )
assert( oneInd === 0 )
const tenInd = nums.find( n => n === 10 )
assert( tenInd === -1 )
const trees = new Collection<Tree>( [ { name: 'spruce' }, { name: 'poplar' } ] )
const poplarInd = trees.find( t => t.name === 'poplar' )
assert( poplarInd === -1 )Predicate
The position where to start searching
Returns the first element of the collection, or null if it is empty
const coll = new Collection( [ 'a', 'b', 'c' ] )
assert( coll.first() === 'a' )
coll.clear()
assert( coll.first() === null )Calls a closure on each element of an collection.
interface Counter {
count: number;
increment(): void;
}
const vec: Collection<Counter> = new Collection()
const c: Counter = {
count: 0,
increment: function() {
this.count++
}
}
vec.push( c )
vec.forEach( c => c.increment() )
assert( vec.first().count === 1 )Callback which will be called on each element
Returns an element at the given position or null
Index
const coll = new Collection( [ 'a', 'b', 'c' ] )
assert( coll.get( 2 ) === 'c' )
assert( coll.get( 12 ) === null )Returns reference to inner array of elements
const vec = new Collection( [ 0, 9, 8 ] )
const inner = vec.getInnerRef()
assert( inner[ 2 ] === 8 )
vec.clear()
assert( inner[ 0 ] === undefined )
assert( inner === vec.getInnerRef() )Returns true if the collection contains an element which is the same as the given value.
Uses strict comparison
const vec = new Collection( [ 7, 8, 9 ] )
assert( vec.has( 8 ) )
assert( !vec.has( 10 ) )
const car1 = { name: 'UAZ' }
const cars = new Collection( [ car1, { name: 'Toyota' }] )
assert( cars.has( { name: 'Toyota' } ) === false )
assert( cars.has( car1 ) === true )Item which is searching for
Returns true if the collection contains no elements
const vec = new Collection( [ [], [] ] )
assert( !vec.isEmpty() )
vec.clear()
assert( vec.isEmpty() )Returns the last element of the collection, or null if it is empty
const coll = new Collection( [ 'a', 'b', 'c' ] )
assert( coll.last() === 'c' )
coll.clear()
assert( coll.last() === null )Returns index of last element or -1
const vec = new Collection()
assert( vec.lastIndex() === -1 )
vec.push( [ 2, 3 ] )
assert( vec.lastIndex() === 1 )
assert( vec.lastIndex() === ( vec.length - 1 ) )Produces a new instance of current type of collection by calling given closure on each element of the original collection and yielding return values of this closure
const coll = new Collection<number>( [ 1, 2 ] )
const doubleStrColl = coll.map( ( n: number ): string => ( n * 2 ).toString() )
assert( doubleStrColl.first() === '2' )
assert( doubleStrColl.last() === '4' )
const indexes = new Collection([ { i: 1, i: 3 } ] )
const indexesRenamed = indexes.map( ( item ) => ( { index: item.i } ) )
assert( indexesRenamed.first().index === 1 )
assert( indexesRenamed.first().i === undefined )Return type of the callback and consequently type of items in generated collection
Callback which will be called on each element
Produces a new Array<R> by calling given closure on each element of the original collection
and collecting return values of this closure
Like map but returns Array instead of collection
const coll = new Collection<number>( [ 1, 2 ] )
const doubleStrArr = coll.mapArr( ( n: number ): string => ( n * 2 ).toString() )
assert( doubleStrArr[ 0 ] === '2' )
assert( doubleStrArr[ 1 ] === '4' )
const towns = new Collection( [ { name: 'Sydney' }, { name: 'Baghdad' } ] )
const names = towns.mapArr( t => t.name )
assert( names.length === 2 && names[ 1 ] === 'Baghdad' )Return type of the callback and consequently type of items in generated array
Callback which will be called on each element
Removes the last element from the collection and returns it.
Or return null if collection is empty
const chars = new Collection( [ 'o', 'p', 'q' ] )
const last = chars.pop()
assert( last === 'q' )
assert( chars.length === 2 ) // [ 'o', 'p' ]Appends an element(s) to the back of a collection
const vec = new Collection( [ 'd', 'e', 'w' ] )
assert( vec.last() === 'w' )
vec.push( 'a' )
assert( vec.last() === 'a' )
vec.push( [ 'x', 'y', 'z' ] )
assert( vec.length === 7 )Element or array of elements to append
Appends an element(s) to the back of a collection only if element is not exists in collection
Uses simple strict comparison ( itemA === itemB ) for checking
const nums = new Collection( [ 1, 2, 3 ] )
nums.pushUniq( [ 4, 3, 1, 5 ] ) // 3 and 1 will not be appended
assert( nums.length === 5 )
const trees = new Collection( [ { name: 'spruce' }, { name: 'pine' } ] )
trees.pushUniq( [ { name: 'poplar' }, { name: 'spruce' } ] ) // all elements will be appended
assert( trees.length === 4 )
assert( trees.last().name === 'spruce' )Element or array of elements to append
Appends an element(s) to the back of a collection only if element is not exists in collection
Uses given compare function to check existing. Comparator must return boolean
If for some pair of elements (inner and given) compare function returns true, given element will not be added
const nums = new Collection( [ 1, 2, 3 ] )
nums.pushUniqBy(
[ 4, 3, 1, 5 ],
( innerItem: number, externalItem: number ): boolean => innerItem === externalItem
)
// 3 and 1 will not be appended. For primitives this example is the same as `pushUniq`
assert( nums.length === 5 )
type Tree = { name: string }
const trees = new Collection<Tree>( [ { name: 'spruce' }, { name: 'pine' } ] )
trees.pushUniqBy( [ {
name: 'poplar'
}, {
name: 'spruce'
} ], ( itA: Tree, itB: Tree ): boolean => {
return itA.name === itB.name
} )
// second spruce will not be added
assert( trees.length === 3 )
assert( trees.last().name === 'poplar' )Element or array of elements to append
Callback that will be compare given elements and existing in collection elements. Must return boolean
Removes and returns the element at position index within the vector
const vec: Collection<string> = new Collection( [ 'x', 'y', 'z' ] )
const y = vec.remove( 1 )
assert( y === 'y' && vec.length === 2 )
const a = vec.remove( 5 )
assert( a === null && vec.length === 2 )Index
Searches for an element that satisfies a predicate. And if some is matches removes and returns it. Stops after first found element
const vec = new Collection( [ [ 'a' ], [ 'b', 'c' ], [ 'd' ] ] )
vec.removeBy( it => it.length === 2 ) // removes second array
assert( vec.length === 2 )
const first = vec.removeBy( it => it.length === 1 ) // removes just first array
assert( first[ 0 ] === 'a' )
assert( vec.length === 1 )Predicate
Creates a new collection by repeating all elements num times.
const chars = new Collection( [ 'a', 'z' ] )
const repeated = chars.repeat( 3 )
assert.deepEqual( repeated.toArray(), [ 'a', 'z', 'a', 'z', 'a', 'z' ] )Resets all items in collection
null it will be the same as clearconst vec = new Collection( [ 'a', 'b', 'c' ] )
vec.reset( [ 'x', 'y', 'z' ] )
assert( vec.last() === 'z' && vec.first() === 'x' )
vec.reset( null )
assert( vec.isEmpty() )Retains only the elements specified by the predicate.
In other words, remove all elements for which predicate return false.
Like a {@link filter} but operates in place. Returns Array of removed elements.
const nums = new Collection( [ 1, 79, 5, 42, 3 ] )
nums.retainBy( ( n ) => n > 10 )
assert( nums.length === 2 )
assert( nums.first() === 79 && nums.last() === 42 )Predicate
Searches for an element in the collection from the right, returning it or null
See findBy
const arrays = new Collection( [ [ 'a' ], [ 'b', 'c' ], [ 'd' ] ] )
const arrWithOneItem = arrays.rfindBy( a => a.length === 1 )
assert( arrWithOneItem[ 0 ] === 'd' )Predicate
The position where to start searching
Searches for an element in the collection from the right, returning its index or -1
See findIndexBy
const arrays = new Collection( [ [ 'a' ], [ 'b', 'c' ], [ 'd' ] ] )
const arrWithOneItemIndex = arrays.rfindIndexBy( a => a.length === 1 )
assert( arrWithOneItemIndex === 2 )Predicate
The position where to start searching
Replaces element at the given position with new element
If index is out of current collection range returns false
const coll = new Collection( [ 'a', 'b', 'c' ] )
coll.set( 0, 'x' )
assert( coll.first() === 'x' )
const isSetted = coll.set( 10, 'z' )
assert( !isSetted && coll.length === 3 )Index
Removes the first element from the collection and returns it.
Or return null if collection is empty
const chars = new Collection( [ 'o', 'p', 'q' ] )
const first = chars.shift()
assert( first === 'o' )
assert( chars.length === 2 ) // [ 'p', 'q' ]Shuffles the collection by using Fisher-Yates algorithm.
const vec = new Collection( [ 1, 2, 3 ] )
vec.shuffle()
assert( true ) // who knows in what sequence these numbers are nowSwaps two elements in the collection
Returns false if indexA or indexB are out of bounds.
const nums = new Collection( [ 1, 2, 3 ] )
nums.swap( 0, 2 )
assert( nums.first() === 3 && nums.last() === 1 )
const isSwapped = nums.swap( 0, 4 )
assert( isSwapped === false )index of the first element
index of the second element
Returns new array of existing elements, without deep copying
const car = { id: 1, name: 'UAZ' }
const vec = new Collection()
vec.push( car )
const arr = vec.toArray()
assert( Array.isArray( arr ) )
assert( arr[ 0 ] === car )Returns json string of inner array of elements.
It is unlikely, but it is still possible that the JSON.stringify ends with an error,
in that case toJSON will return null
const colors = new Collection( [ 'red', 'green' ] )
const json = colors.toJSON()
assert( json === "[\"red\",\"green\"]" )Shortens the collection, keeping the first len elements and dropping the rest.
If len is greater than the vector's current length, this has no effect.
Returns true if collection truncated.
const chars = new Collection( [ 'a', 'b', 'c', 'd' ] )
chars.truncate( 2 )
assert.deepEqual( chars.toArray(), [ 'a', 'b' ] )Expected length of collection
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