BFF Module: bff/list

Maintains a list of items. The idea is to stay as true as possible to the native Array interface, but to augment its usefulness by triggering events whenever the list is updated, as well as adding convenience functions for mutating the List in place.

The exported List constructor can be used as-is, in which case a generic List will be created. This is a quite common use case. Alternatively, a List "subclass" constructor can be created by calling List.withProperties(...). This second approach provides the possibility to add custom calculated properties to the list. See module:bff/list#withProperties for more details.

new (require("bff/list"))( [items])

Creates a new List, with an optional list or array of initial items.

Parameters:

Name	Type	Argument	Description
`items`	Array \| List	<optional>	Items that will be added to the List on creation.

Mixes In:

Source:

list.js, line 798

Methods

<static> withProperties(schema)

Creates a new List constructor function, that will create List instances with the property schema
provided to this function

Parameters:

Name	Type	Description
`schema`	Object	An object describing the properties that will be part of all new instances created by the returned constructor function. The property descriptions should be on the same format at the schema specified for module:bff/record.withProperties, with the only exception that setters are not allowed.

Source:

list.js, line 808

Returns:

New constructor function based on the provided schema.

Type: function

addEventListener(eventName)

Augmented version of bff/event-emitter#addEventListener that provides the option to listen to events emitted from any item in the List. To add a listener to an item event, prepend the event name with 'item:'. For instance, to listen for the 'change' event on all the list items (even ones added after the listener was created), add a listener for the 'item:change' event.

Parameters:

Name	Type	Description
`eventName`	string	Identifier string for the event.

Source:

list.js, line 668

clear()

Mutates the List by removing all items.

Source:

list.js, line 508

Fires:

Returns:

The List, now empty.

Type: List

concat(value)

Returns a new List comprised of the List on which it is called joined with the List(s), Array(s) and/or value(s) provided as arguments. Mirrors the behavior of Array.concat.

Parameters:

Name	Type	Argument	Description
`value`	any	<repeatable>	A List, Array or value that will be concatenated with the original List. Lists and Arrays will be deconstructed and each item added to the new List.

Source:

list.js, line 453

Returns:

The new List.

Type: List

every(predicate [, thisArg])

Mirrors Array.every behavior.

Parameters:

Name	Type	Argument	Description
`predicate`	module:bff/list~predicateCallback		Executed once per List item.
`thisArg`	any	<optional>	Value to use as "this" when executing callback.

Source:

list.js, line 331

Returns:

true if all items passes the predicate test, false otherwise.

Type: boolean

filter(predicate)

Creates a new List with all items that pass the test implemented by the predicate function test. The original list is unchanged. Mirrors the behavior of Array.filter.

Parameters:

Name	Type	Description
`predicate`	module:bff/list~predicateCallback	Executed once per List item.

Source:

list.js, line 415

Returns:

The new List.

Type: List

filterMut(predicate [, thisArg])

Mutates the List by removing all items that does not pass the predicate function test.

Parameters:

Name	Type	Argument	Description
`predicate`	module:bff/list~predicateCallback		Called once per List item to determine whether the item should be removed.
`thisArg`	any	<optional>	Value to use as "this" when executing predicate callback.

Source:

list.js, line 472

Fires:

Returns:

The filtered List.

Type: List

find(predicate)

Returns the first item in the List that passes the predicate function test, or undefined if no item passes.

Parameters:

Name	Type	Description
`predicate`	module:bff/list~predicateCallback	Called once per List item to in order to find a matching item.

Source:

list.js, line 590

Returns:

The matching item, if any.

Type: any | undefined

findIndex(predicate)

Returns the index of the first item in the List that passes the predicate function test, or -1 if no item passes.

Parameters:

Name	Type	Description
`predicate`	module:bff/list~predicateCallback	Called once per List item to in order to find a matching item.

Source:

list.js, line 604

Returns:

The position of the matching item, or -1 if none matches.

Type: number

forEach(callback [, thisArg])

Executes the given function once per List item. Mirrors Array.forEach behavior.

Parameters:

Name	Type	Argument	Description
`callback`	module:bff/list~forEachCallback		The function that will be called once per List item.
`thisArg`	any	<optional>	Value to use as "this" when executing callback.

Source:

list.js, line 323

includes(item [, fromIndex])

Returns whether the provided item is part of the List.

Parameters:

Name	Type	Argument	Description
`item`	any
`fromIndex`	number	<optional>	The index to start the search at. If the index is greater than or equal to the List's length, -1 is returned, which means the List will not be searched. If the provided index value is a negative number, it is taken as the offset from the end of the List.

Source:

list.js, line 620

Returns:

True if the item is part of the List, false otherwise.

Type: boolean

indexOf(searchItem [, fromIndex])

Mirrors Array.indexOf behavior.

Parameters:

Name	Type	Argument	Description
`searchItem`	any		The item to locate within the List.
`fromIndex`	number	<optional>	The index to start the search at. If the index is greater than or equal to the List's length, -1 is returned, which means the List will not be searched. If the provided index value is a negative number, it is taken as the offset from the end of the List.

Source:

list.js, line 349

Returns:

The first index at which a given item can be found in the List, or -1 if it is not present.

Type: number

join( [separator])

Parameters:

Name	Type	Argument	Description
`separator`	string	<optional>	Specifies a string to separate each item of the List. If omitted, the List items are separated with a comma. Mirrors Array.join behavior.

Source:

list.js, line 366

Returns:

The stringified List items, joined by the 'separator' string argument.

Type: string

lastIndexOf(searchItem [, fromIndex])

Parameters:

Name	Type	Argument	Description
`searchItem`	any		The item to locate within the List.
`fromIndex`	number	<optional>	The index at which to start searching backwards. Defaults to the List's length minus one, i.e. the whole List will be searched. If the index is greater than or equal to the length of the List, the whole List will be searched. If negative, it is taken as the offset from the end of the List. Mirrors Array.lastIndexOf behavior.

Source:

list.js, line 358

Returns:

The last index at which a given item can be found in the List, or -1 if it is not present.

Type: number

map(callback [, thisArg])

Creates a new List with the results of calling a provided callback function on every element in the List. Mirrors the behavior of Array.map.

Parameters:

Name	Type	Argument	Description
`callback`	module:bff/module~mapCallback		Executed once per List item.
`thisArg`	any	<optional>	Value to use as "this" when executing callback.

Source:

list.js, line 434

Returns:

The new List.

Type: List

mapMut(callback [, thisArg])

Replaces all items in the List with new items, generated by the callback function.

Parameters:

Name	Type	Argument	Description
`callback`	module:bff/module~mapCallback		Executed once per List item to produce new items.
`thisArg`	any	<optional>	Value to use as "this" when executing callback.

Source:

list.js, line 575

Fires:

module:bff/list#item:replaced

Returns:

The List, with all items updated.

Type: List

pop()

Remove and return one item from the end of the List. Mirrors Array.pop behavior.

Source:

list.js, line 231

Fires:

Returns:

Removed item

Type: any

propertiesToJSON()

Returns a newly created Object containing the List's deep copied properties.

Source:

list.js, line 659

Returns:

Type: Object

push(item)

Add one or more items to the end of the List. Mirrors Array.push behavior.

Parameters:

Name	Type	Argument	Description
`item`	any	<repeatable>	Each item argument will be pushed onto the List.

Source:

list.js, line 180

Fires:

Returns:

Updated List length

Type: number

pushAll(items)

Mutates the List by adding the items comprising the provided List or Array to the end of the List.

Parameters:

Name	Type	Description
`items`	module:bff/list \| Array	The items that will be appended to the List.

Source:

list.js, line 520

Fires:

Returns:

The List, with new items appended.

Type: List

reduce(callback, initialValue)

Applies a function against an accumulator and each value of the List (from left-to-right) to reduce it to a single value. Mirrors Array.reduce behavior.

Parameters:

Name	Type	Description
`callback`	module:bff/list~reduceCallback	The function that will be called once per List item.
`initialValue`	any	Value to use as the first argument to the first call of the callback.

Source:

list.js, line 373

Returns:

Aggregated value

Type: any

reduceRight(callback, initialValue)

Applies a function against an accumulator and each value of the List (from right-to-left) to reduce it to a single value. Mirrors Array.reduceRight behavior.

Parameters:

Name	Type	Description
`callback`	module:bff/list~reduceCallback	The function that will be called once per List item.
`initialValue`	any	Value to use as the first argument to the first call of the callback.

Source:

list.js, line 382

Returns:

Aggregated value

Type: any

remove(item)

Mutates the List by removing all occurances of the provided item.

Parameters:

Name	Type	Description
`item`	any	The item to remove from the list.

Source:

list.js, line 497

Fires:

Returns:

The List, without any occurances of 'item'.

Type: List

removeEventListener(eventName)

Augmented version of bff/event-emitter#removeEventListener that provides functionality for removing "item" event listeners, e.g. for stop listening to events like "items:change".

Parameters:

Name	Type	Description
`eventName`	string	Identifier string for the event.

Source:

list.js, line 688

reverse()

Reverses the List in place. Mirros the behavior of Array.reverse. No events are emitted by this operation.

Source:

list.js, line 404

shift()

Remove and return one item from the beginning of the List. Mirrors Array.shift behavior.

Source:

list.js, line 253

Fires:

Returns:

Removed item

Type: any

slice( [begin] [, end])

Creates a new List from the range of current items specified by the begin and end arguments. Mirrors the behavior of Array.slice.

Parameters:

Name	Type	Argument	Description
`begin`	number	<optional>	Index that specifies the beginning of the range. Inclusive. A negative index will be relative to the end of the List instead of the beginning.
`end`	number	<optional>	Index that specifies the end of the range. Exclusive. A negative index will be relative to the end of the List instead of the beginning.

Source:

list.js, line 423

Returns:

The new List.

Type: List

sliceMut( [begin] [, end])

Mutates the List by removing all elements outside of range specified by the begin and end arguments.

Parameters:

Name	Type	Argument	Description
`begin`	number	<optional>	Index that specifies the beginning of the range. Inclusive. A negative index will be relative to the end of the List instead of the beginning.
`end`	number	<optional>	Index that specifies the end of the range. Exclusive. A negative index will be relative to the end of the List instead of the beginning.

Source:

list.js, line 537

Fires:

Returns:

The List, sans the items outside of the specified range.

Type: List

some(predicate [, thisArg])

Mirrors Array.some behavior.

Parameters:

Name	Type	Argument	Description
`predicate`	module:bff/list~predicateCallback		Executed once per List item.
`thisArg`	any	<optional>	Value to use as "this" when executing callback.

Source:

list.js, line 340

Returns:

true if at least one item passes the predicate test, false otherwise.

Type: boolean

sort( [comparator])

Sorts the items of the List in place. The sort is not necessarily stable. The default sort order is according to string Unicode code points, unless a custom comparator finction is provided. Mirrors the behavior of Array.sort. No events are emitted by this operation.

Parameters:

Name	Type	Argument	Description
`comparator`	module:bff/list~compareFunction	<optional>	A function that specifies the ordering of two arbitrary List items. Called multiple times in order to produce a total ordering of the items.

Source:

list.js, line 396

Returns:

The sorted list.

Type: List

splice(start, nItemsToRemove [, itemToAdd])

Changes the content of the List by removing existing items and/or adding new items. Mirrors Array.splice behavior.

Parameters:

Name	Type	Argument	Description
`start`	number		Index at which to start changing the array. If greater than the length of the array, actual starting index will be set to the length of the array. If negative, will begin that many items from the end.
`nItemsToRemove`	number		An integer indicating the number of old array items to remove. If nItemsToRemove is greater than the number of items left in the array starting at start, then all of the items through the end of the array will be deleted.
`itemToAdd`	any	<optional> <repeatable>	Item that will be added to the array, starting at the index specified in the first argument.

Source:

list.js, line 280

Fires:

Returns:

Array of removed items

Type: Array.<any>

toArray()

Returns an newly created Array, containing all the items of the List. List properties are not copied to the Array object. The items are copied shallowly.

Source:

list.js, line 635

Returns:

Type: Array

toJSON()

Returns a newly created Array representation of the List, containing deep copies of all the List's items, but not its properties.

Source:

list.js, line 644

Returns:

Type: Array

toString()

Source:

list.js, line 710

Returns:

A human readable string representation of the List.

Type: string

unshift(item)

Add one or more items to the beginning of the List. Mirrors Array.unshift behavior.

Parameters:

Name	Type	Argument	Description
`item`	any	<repeatable>	Each item argument will be pushed onto the List.

Source:

list.js, line 206

Fires:

Returns:

Updated List length

Type: Number

Type Definitions

compareFunction(itemA, itemB)

Compares itemA and itemB arguments according to some sorting criterion. Should return -1 if itemA comes before itemB, 0 if itemA is equal to itemB, 1 if itemB comes before itemA.

Parameters:

Name	Type	Description
`itemA`	any	A list item.
`itemB`	any	Another list item.

Source:

list.js, line 85

Returns:

Type: number

forEachCallback(item, index, list)

Parameters:

Name	Type	Description
`item`	any	Current List item.
`index`	number	Item position in List.
`list`	module:bff/list	List being iterated over.

Source:

list.js, line 53

mapCallback(item, index, list)

Parameters:

Name	Type	Description
`item`	any	Current List item.
`index`	number	Item position in List.
`list`	module:bff/list	List being iterated over.

Source:

list.js, line 60

Returns:

Transformed object.

Type: any

predicateCallback(item, index, list)

Parameters:

Name	Type	Description
`item`	any	Current List item.
`index`	number	Item position in List.
`list`	module:bff/list	List being iterated over.

Source:

list.js, line 68

Returns:

true if the item passes the test, false otherwise

Type: boolean

reduceCallback(previousItem, item, index, list)

Parameters:

Name	Type	Description
`previousItem`	any	The value previously returned in the last invocation of the callback, or initialValue, if supplied. Usually an aggregate of previous items.
`item`	any	Current List item being processed.
`index`	number	Item position in List.
`list`	module:bff/list	List being iterated over.

Source:

list.js, line 76

Returns:

The aggregated value.

Type: any

Events

change:length

Parameters:

Name	Type	Description
`newLength`	number	The current length of the List.
`oldLength`	number	The previous length of the List.
`list`	module:bff/list	The List whose length has changed.

Source:

list.js, line 39

item:added

Parameters:

Name	Type	Description
`item`	any	The item that was added to the List.
`index`	number	The position withing the List where the item was added.
`list`	module:bff/list	The List to which the item was added.

Source:

list.js, line 17

item:removed

Parameters:

Name	Type	Description
`item`	any	The item that was removed from the List.
`index`	number	The position withing the List where the item was removed.
`list`	module:bff/list	The List from which the item was removed.

Source:

list.js, line 32

item:replaced

Parameters:

Name	Type	Description
`newItem`	any	The item that was added to the List.
`oldItem`	any	The item that was removed from the List.
`index`	number	The position withing the List where the item was replaced.
`list`	module:bff/list	The List in which the item was replaced.

Source:

list.js, line 24