Optional

Validates if value is undefined or matches the expectation.

example

import {

check,

define,

Class,

Optional,

ValidationError,

convert,

validate,

PropTypes,

} from 'typend';

@define()

class Sandwich {

pickles?: boolean;

}

expect(convert<Sandwich>()).to.be.eql(

new Class(Sandwich, {

pickles: PropTypes.equal(Boolean).isOptional,

})

);

check<undefined | string>('foo');

check<undefined | string>(undefined);

expect(() => check<undefined | number>('foo')).to.throw(ValidationError);

validate(undefined, PropTypes.equal(String).isOptional);

validate('foo', PropTypes.instanceOf(String).isOptional);

validate('foo', new Optional(String));

expect(() => validate('foo', PropTypes.equal(Number).isOptional)).to.throw(

ValidationError

);

Type parameters

▪ T

▪ T

▪ T

▪ T

▪ T

▪ T

▪ T

▪ T

▪ T

▪ T

Hierarchy

• Array

• Array

  ↳ Optional

Implements

• Pattern
• Pattern

Indexable

• [ n: number]: T

Validates if value is undefined or matches the expectation.

example

import {

check,

define,

Class,

Optional,

ValidationError,

convert,

validate,

PropTypes,

} from 'typend';

@define()

class Sandwich {

pickles?: boolean;

}

expect(convert<Sandwich>()).to.be.eql(

new Class(Sandwich, {

pickles: PropTypes.equal(Boolean).isOptional,

})

);

check<undefined | string>('foo');

check<undefined | string>(undefined);

expect(() => check<undefined | number>('foo')).to.throw(ValidationError);

validate(undefined, PropTypes.equal(String).isOptional);

validate('foo', PropTypes.instanceOf(String).isOptional);

validate('foo', new Optional(String));

expect(() => validate('foo', PropTypes.equal(Number).isOptional)).to.throw(

ValidationError

);

Index

Constructors

• constructor

Properties

• length
• Array
• describer
• kind

Methods

• [Symbol.iterator]
• [Symbol.unscopables]
• concat
• copyWithin
• describe
• entries
• every
• fill
• filter
• find
• findIndex
• forEach
• getInitializer
• getKind
• hasInitializer
• includes
• indexOf
• join
• keys
• lastIndexOf
• map
• pop
• push
• reduce
• reduceRight
• reverse
• setInitializer
• shift
• slice
• some
• sort
• splice
• toLocaleString
• toString
• unshift
• values
• getDescriber
• setDescriber

Constructors

constructor

+ new Optional(...expectations: any[]): Optional

Creates an instance of a WrapperPattern. Creates an instance of a WrapperPattern.

Parameters:

Name	Type	Description
...expectations	any[]	Expectations that will be assigned to pattern container.

Returns: Optional

Properties

length

• length: number

Inherited from Optional.length

Overrides Optional.length

Gets or sets the length of the array. This is a number one higher than the highest index in the array.

---

Static Array

▪ Array: ArrayConstructor

---

Static describer

▪ describer: Describer

---

Static kind

▪ kind: KINDS = KINDS.OPTIONAL

Methods

[Symbol.iterator]

▸ [Symbol.iterator](): IterableIterator‹T›

Inherited from Optional.[Symbol.iterator]

Overrides Optional.[Symbol.iterator]

Iterator

Returns: IterableIterator‹T›

---

[Symbol.unscopables]

▸ [Symbol.unscopables](): object

Inherited from Optional.[Symbol.unscopables]

Overrides Optional.[Symbol.unscopables]

Returns an object whose properties have the value 'true' when they will be absent when used in a 'with' statement.

Returns: object

• copyWithin: boolean

• entries: boolean

• fill: boolean

• find: boolean

• findIndex: boolean

• keys: boolean

• values: boolean

---

concat

▸ concat(...items: ConcatArray‹T›[]): T[]

Inherited from Optional.concat

Overrides Optional.concat

Combines two or more arrays. This method returns a new array without modifying any existing arrays.

Parameters:

Name	Type	Description
...items	ConcatArray‹T›[]	Additional arrays and/or items to add to the end of the array.

Returns: T[]

▸ concat(...items: T | ConcatArray‹T›[]): T[]

Inherited from Optional.concat

Overrides Optional.concat

Combines two or more arrays. This method returns a new array without modifying any existing arrays.

Parameters:

Name	Type	Description
...items	T | ConcatArray‹T›[]	Additional arrays and/or items to add to the end of the array.

Returns: T[]

---

copyWithin

▸ copyWithin(target: number, start: number, end?: number): this

Inherited from Optional.copyWithin

Overrides Optional.copyWithin

Returns the this object after copying a section of the array identified by start and end to the same array starting at position target

Parameters:

Name	Type	Description
target	number	If target is negative, it is treated as length+target where length is the length of the array.
start	number	If start is negative, it is treated as length+start. If end is negative, it is treated as length+end.
end?	number	If not specified, length of the this object is used as its default value.

Returns: this

---

describe

▸ describe(value: any): string

Describes value in human readable form.

Parameters:

Name	Type	Description
value	any	Value that needs to be described.

Returns: string

Human readable value described as a string.

---

entries

▸ entries(): IterableIterator‹[]›

Inherited from Optional.entries

Overrides Optional.entries

Returns an iterable of key, value pairs for every entry in the array

Returns: IterableIterator‹[]›

---

every

▸ every‹S›(predicate: function, thisArg?: any): this is S[]

Inherited from Optional.every

Overrides Optional.every

Determines whether all the members of an array satisfy the specified test.

Type parameters:

▪ S: T

Parameters:

▪ predicate: function

A function that accepts up to three arguments. The every method calls the predicate function for each element in the array until the predicate returns a value which is coercible to the Boolean value false, or until the end of the array.

▸ (value: T, index: number, array: T[]): value is S

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

Returns: this is S[]

▸ every(predicate: function, thisArg?: any): boolean

Inherited from Optional.every

Overrides Optional.every

Determines whether all the members of an array satisfy the specified test.

Parameters:

▪ predicate: function

A function that accepts up to three arguments. The every method calls the predicate function for each element in the array until the predicate returns a value which is coercible to the Boolean value false, or until the end of the array.

▸ (value: T, index: number, array: T[]): unknown

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

Returns: boolean

---

fill

▸ fill(value: T, start?: number, end?: number): this

Inherited from Optional.fill

Overrides Optional.fill

Changes all array elements from start to end index to a static value and returns the modified array

Parameters:

Name	Type	Description
value	T	value to fill array section with
start?	number	index to start filling the array at. If start is negative, it is treated as length+start where length is the length of the array.
end?	number	index to stop filling the array at. If end is negative, it is treated as length+end.

Returns: this

---

filter

▸ filter‹S›(predicate: function, thisArg?: any): S[]

Inherited from Optional.filter

Overrides Optional.filter

Returns the elements of an array that meet the condition specified in a callback function.

Type parameters:

▪ S: T

Parameters:

▪ predicate: function

A function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.

▸ (value: T, index: number, array: T[]): value is S

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

Returns: S[]

▸ filter(predicate: function, thisArg?: any): T[]

Inherited from Optional.filter

Overrides Optional.filter

Returns the elements of an array that meet the condition specified in a callback function.

Parameters:

▪ predicate: function

A function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.

▸ (value: T, index: number, array: T[]): unknown

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

Returns: T[]

---

find

▸ find‹S›(predicate: function, thisArg?: any): S | undefined

Inherited from Optional.find

Overrides Optional.find

Returns the value of the first element in the array where predicate is true, and undefined otherwise.

Type parameters:

▪ S: T

Parameters:

▪ predicate: function

find calls predicate once for each element of the array, in ascending order, until it finds one where predicate returns true. If such an element is found, find immediately returns that element value. Otherwise, find returns undefined.

▸ (this: void, value: T, index: number, obj: T[]): value is S

Parameters:

Name	Type
this	void
value	T
index	number
obj	T[]

▪Optional thisArg: any

If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

Returns: S | undefined

▸ find(predicate: function, thisArg?: any): T | undefined

Inherited from Optional.find

Overrides Optional.find

Parameters:

▪ predicate: function

▸ (value: T, index: number, obj: T[]): unknown

Parameters:

Name	Type
value	T
index	number
obj	T[]

▪Optional thisArg: any

Returns: T | undefined

---

findIndex

▸ findIndex(predicate: function, thisArg?: any): number

Inherited from Optional.findIndex

Overrides Optional.findIndex

Returns the index of the first element in the array where predicate is true, and -1 otherwise.

Parameters:

▪ predicate: function

find calls predicate once for each element of the array, in ascending order, until it finds one where predicate returns true. If such an element is found, findIndex immediately returns that element index. Otherwise, findIndex returns -1.

▸ (value: T, index: number, obj: T[]): unknown

Parameters:

Name	Type
value	T
index	number
obj	T[]

▪Optional thisArg: any

If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

Returns: number

---

forEach

▸ forEach(callbackfn: function, thisArg?: any): void

Inherited from Optional.forEach

Overrides Optional.forEach

Performs the specified action for each element in an array.

Parameters:

▪ callbackfn: function

A function that accepts up to three arguments. forEach calls the callbackfn function one time for each element in the array.

▸ (value: T, index: number, array: T[]): void

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns: void

---

getInitializer

▸ getInitializer(): any | undefined

Implementation of Pattern

Returns the initializing value.

Returns: any | undefined

Initializing value, else undefined.

---

getKind

▸ getKind(): string

Implementation of Pattern

Returns for which kind pattern is created.

Returns: string

Kind represented as a string.

---

hasInitializer

▸ hasInitializer(): boolean

Implementation of Pattern

Evaluates if initializing value was assigned to type.

Returns: boolean

Returns true if initializing value is set for type, else false.

---

includes

▸ includes(searchElement: T, fromIndex?: number): boolean

Inherited from Optional.includes

Overrides Optional.includes

Determines whether an array includes a certain element, returning true or false as appropriate.

Parameters:

Name	Type	Description
searchElement	T	The element to search for.
fromIndex?	number	The position in this array at which to begin searching for searchElement.

Returns: boolean

---

indexOf

▸ indexOf(searchElement: T, fromIndex?: number): number

Inherited from Optional.indexOf

Overrides Optional.indexOf

Returns the index of the first occurrence of a value in an array, or -1 if it is not present.

Parameters:

Name	Type	Description
searchElement	T	The value to locate in the array.
fromIndex?	number	The array index at which to begin the search. If fromIndex is omitted, the search starts at index 0.

Returns: number

---

join

▸ join(separator?: string): string

Inherited from Optional.join

Overrides Optional.join

Adds all the elements of an array into a string, separated by the specified separator string.

Parameters:

Name	Type	Description
separator?	string	A string used to separate one element of the array from the next in the resulting string. If omitted, the array elements are separated with a comma.

Returns: string

---

keys

▸ keys(): IterableIterator‹number›

Inherited from Optional.keys

Overrides Optional.keys

Returns an iterable of keys in the array

Returns: IterableIterator‹number›

---

lastIndexOf

▸ lastIndexOf(searchElement: T, fromIndex?: number): number

Inherited from Optional.lastIndexOf

Overrides Optional.lastIndexOf

Returns the index of the last occurrence of a specified value in an array, or -1 if it is not present.

Parameters:

Name	Type	Description
searchElement	T	The value to locate in the array.
fromIndex?	number	The array index at which to begin searching backward. If fromIndex is omitted, the search starts at the last index in the array.

Returns: number

---

map

▸ map‹U›(callbackfn: function, thisArg?: any): U[]

Inherited from Optional.map

Overrides Optional.map

Calls a defined callback function on each element of an array, and returns an array that contains the results.

Type parameters:

▪ U

Parameters:

▪ callbackfn: function

A function that accepts up to three arguments. The map method calls the callbackfn function one time for each element in the array.

▸ (value: T, index: number, array: T[]): U

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

Returns: U[]

---

pop

▸ pop(): T | undefined

Inherited from Optional.pop

Overrides Optional.pop

Removes the last element from an array and returns it. If the array is empty, undefined is returned and the array is not modified.

Returns: T | undefined

---

push

▸ push(...items: T[]): number

Inherited from Optional.push

Overrides Optional.push

Appends new elements to the end of an array, and returns the new length of the array.

Parameters:

Name	Type	Description
...items	T[]	New elements to add to the array.

Returns: number

---

reduce

▸ reduce(callbackfn: function): T

Inherited from Optional.reduce

Overrides Optional.reduce

Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.

Parameters:

▪ callbackfn: function

A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.

▸ (previousValue: T, currentValue: T, currentIndex: number, array: T[]): T

Parameters:

Name	Type
previousValue	T
currentValue	T
currentIndex	number
array	T[]

Returns: T

▸ reduce(callbackfn: function, initialValue: T): T

Inherited from Optional.reduce

Overrides Optional.reduce

Parameters:

▪ callbackfn: function

▸ (previousValue: T, currentValue: T, currentIndex: number, array: T[]): T

Parameters:

Name	Type
previousValue	T
currentValue	T
currentIndex	number
array	T[]

▪ initialValue: T

Returns: T

▸ reduce‹U›(callbackfn: function, initialValue: U): U

Inherited from Optional.reduce

Overrides Optional.reduce

Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.

Type parameters:

▪ U

Parameters:

▪ callbackfn: function

A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.

▸ (previousValue: U, currentValue: T, currentIndex: number, array: T[]): U

Parameters:

Name	Type
previousValue	U
currentValue	T
currentIndex	number
array	T[]

▪ initialValue: U

If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.

Returns: U

---

reduceRight

▸ reduceRight(callbackfn: function): T

Inherited from Optional.reduceRight

Overrides Optional.reduceRight

Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.

Parameters:

▪ callbackfn: function

A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.

▸ (previousValue: T, currentValue: T, currentIndex: number, array: T[]): T

Parameters:

Name	Type
previousValue	T
currentValue	T
currentIndex	number
array	T[]

Returns: T

▸ reduceRight(callbackfn: function, initialValue: T): T

Inherited from Optional.reduceRight

Overrides Optional.reduceRight

Parameters:

▪ callbackfn: function

▸ (previousValue: T, currentValue: T, currentIndex: number, array: T[]): T

Parameters:

Name	Type
previousValue	T
currentValue	T
currentIndex	number
array	T[]

▪ initialValue: T

Returns: T

▸ reduceRight‹U›(callbackfn: function, initialValue: U): U

Inherited from Optional.reduceRight

Overrides Optional.reduceRight

Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.

Type parameters:

▪ U

Parameters:

▪ callbackfn: function

A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.

▸ (previousValue: U, currentValue: T, currentIndex: number, array: T[]): U

Parameters:

Name	Type
previousValue	U
currentValue	T
currentIndex	number
array	T[]

▪ initialValue: U

If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.

Returns: U

---

reverse

▸ reverse(): T[]

Inherited from Optional.reverse

Overrides Optional.reverse

Reverses the elements in an array in place. This method mutates the array and returns a reference to the same array.

Returns: T[]

---

setInitializer

▸ setInitializer(initializer: any): void

Implementation of Pattern

Sets as non-enumerable the initializing value for type if present on conversion.

Parameters:

Name	Type	Description
initializer	any	Initializer value provided on conversion.

Returns: void

---

shift

▸ shift(): T | undefined

Inherited from Optional.shift

Overrides Optional.shift

Removes the first element from an array and returns it. If the array is empty, undefined is returned and the array is not modified.

Returns: T | undefined

---

slice

▸ slice(start?: number, end?: number): T[]

Inherited from Optional.slice

Overrides Optional.slice

Returns a copy of a section of an array. For both start and end, a negative index can be used to indicate an offset from the end of the array. For example, -2 refers to the second to last element of the array.

Parameters:

Name	Type	Description
start?	number	The beginning index of the specified portion of the array. If start is undefined, then the slice begins at index 0.
end?	number	The end index of the specified portion of the array. This is exclusive of the element at the index 'end'. If end is undefined, then the slice extends to the end of the array.

Returns: T[]

---

some

▸ some(predicate: function, thisArg?: any): boolean

Inherited from Optional.some

Overrides Optional.some

Determines whether the specified callback function returns true for any element of an array.

Parameters:

▪ predicate: function

A function that accepts up to three arguments. The some method calls the predicate function for each element in the array until the predicate returns a value which is coercible to the Boolean value true, or until the end of the array.

▸ (value: T, index: number, array: T[]): unknown

Parameters:

Name	Type
value	T
index	number
array	T[]

▪Optional thisArg: any

An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

Returns: boolean

---

sort

▸ sort(compareFn?: function): this

Inherited from Optional.sort

Overrides Optional.sort

Sorts an array in place. This method mutates the array and returns a reference to the same array.

Parameters:

▪Optional compareFn: function

Function used to determine the order of the elements. It is expected to return a negative value if the first argument is less than the second argument, zero if they're equal, and a positive value otherwise. If omitted, the elements are sorted in ascending, ASCII character order.

[11,2,22,1].sort((a, b) => a - b)

▸ (a: T, b: T): number

Parameters:

Name	Type
a	T
b	T

Returns: this

---

splice

▸ splice(start: number, deleteCount?: number): T[]

Inherited from Optional.splice

Overrides Optional.splice

Removes elements from an array and, if necessary, inserts new elements in their place, returning the deleted elements.

Parameters:

Name	Type	Description
start	number	The zero-based location in the array from which to start removing elements.
deleteCount?	number	The number of elements to remove.

Returns: T[]

An array containing the elements that were deleted.

▸ splice(start: number, deleteCount: number, ...items: T[]): T[]

Inherited from Optional.splice

Overrides Optional.splice

Removes elements from an array and, if necessary, inserts new elements in their place, returning the deleted elements.

Parameters:

Name	Type	Description
start	number	The zero-based location in the array from which to start removing elements.
deleteCount	number	The number of elements to remove.
...items	T[]	Elements to insert into the array in place of the deleted elements.

Returns: T[]

An array containing the elements that were deleted.

---

toLocaleString

▸ toLocaleString(): string

Inherited from Optional.toLocaleString

Overrides Optional.toLocaleString

Returns a string representation of an array. The elements are converted to string using their toLocaleString methods.

Returns: string

---

toString

▸ toString(): string

Inherited from Optional.toString

Overrides Optional.toString

Returns a string representation of an array.

Returns: string

---

unshift

▸ unshift(...items: T[]): number

Inherited from Optional.unshift

Overrides Optional.unshift

Inserts new elements at the start of an array, and returns the new length of the array.

Parameters:

Name	Type	Description
...items	T[]	Elements to insert at the start of the array.

Returns: number

---

values

▸ values(): IterableIterator‹T›

Inherited from Optional.values

Overrides Optional.values

Returns an iterable of values in the array

Returns: IterableIterator‹T›

---

Static getDescriber

▸ getDescriber(): Describer

Returns describing library.

Returns: Describer

Describer library instance.

---

Static setDescriber

▸ setDescriber(describer: Describer): void

Sets describing library.

Parameters:

Name	Type	Description
describer	Describer	Describer library instance.

Returns: void