Interface ReadonlyArray<T>

    interface ReadonlyArray<T> {
        [unscopables]: {
            [unscopables]?: boolean;
            length?: boolean;
            [iterator]?: any;
            at?: any;
            concat?: any;
            entries?: any;
            every?: any;
            filter?: any;
            find?: any;
            findIndex?: any;
            findLast?: any;
            findLastIndex?: any;
            flat?: any;
            flatMap?: any;
            forEach?: any;
            includes?: any;
            indexOf?: any;
            join?: any;
            keys?: any;
            lastIndexOf?: any;
            map?: any;
            reduce?: any;
            reduceRight?: any;
            slice?: any;
            some?: any;
            toLocaleString?: any;
            toReversed?: any;
            toSorted?: any;
            toSpliced?: any;
            toString?: any;
            values?: any;
            with?: any;
        };
        length: number;
        [iterator](): ArrayIterator<T>;
        at(index: number): T;
        concat(...items: ConcatArray<T>[]): T[];
        concat(...items: (T | ConcatArray<T>)[]): T[];
        entries(): ArrayIterator<[number, T]>;
        every<S>(predicate: ((value: T, index: number, array: readonly T[]) => value is S), thisArg?: any): this is readonly S[];
        every(predicate: ((value: T, index: number, array: readonly T[]) => unknown), thisArg?: any): boolean;
        filter<S>(predicate: ((value: T, index: number, array: readonly T[]) => value is S), thisArg?: any): S[];
        filter(predicate: ((value: T, index: number, array: readonly T[]) => unknown), thisArg?: any): T[];
        find<S>(predicate: ((value: T, index: number, obj: readonly T[]) => value is S), thisArg?: any): S;
        find(predicate: ((value: T, index: number, obj: readonly T[]) => unknown), thisArg?: any): T;
        findIndex(predicate: ((value: T, index: number, obj: readonly T[]) => unknown), thisArg?: any): number;
        findLast<S>(predicate: ((value: T, index: number, array: readonly T[]) => value is S), thisArg?: any): S;
        findLast(predicate: ((value: T, index: number, array: readonly T[]) => unknown), thisArg?: any): T;
        findLastIndex(predicate: ((value: T, index: number, array: readonly T[]) => unknown), thisArg?: any): number;
        flat<A, D>(this: A, depth?: D): FlatArray<A, D>[];
        flatMap<U, This>(callback: ((this: This, value: T, index: number, array: T[]) => U | ReadonlyArray<U>), thisArg?: This): U[];
        forEach(callbackfn: ((value: T, index: number, array: readonly T[]) => void), thisArg?: any): void;
        includes(searchElement: T, fromIndex?: number): boolean;
        indexOf(searchElement: T, fromIndex?: number): number;
        join(separator?: string): string;
        keys(): ArrayIterator<number>;
        lastIndexOf(searchElement: T, fromIndex?: number): number;
        map<U>(callbackfn: ((value: T, index: number, array: readonly T[]) => U), thisArg?: any): U[];
        reduce(callbackfn: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T)): T;
        reduce(callbackfn: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T), initialValue: T): T;
        reduce<U>(callbackfn: ((previousValue: U, currentValue: T, currentIndex: number, array: readonly T[]) => U), initialValue: U): U;
        reduceRight(callbackfn: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T)): T;
        reduceRight(callbackfn: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T), initialValue: T): T;
        reduceRight<U>(callbackfn: ((previousValue: U, currentValue: T, currentIndex: number, array: readonly T[]) => U), initialValue: U): U;
        slice(start?: number, end?: number): T[];
        some(predicate: ((value: T, index: number, array: readonly T[]) => unknown), thisArg?: any): boolean;
        toLocaleString(): string;
        toLocaleString(locales: string | string[], options?: NumberFormatOptions & DateTimeFormatOptions): string;
        toReversed(): T[];
        toSorted(compareFn?: ((a: T, b: T) => number)): T[];
        toSpliced(start: number, deleteCount: number, ...items: T[]): T[];
        toSpliced(start: number, deleteCount?: number): T[];
        toString(): string;
        values(): ArrayIterator<T>;
        with(index: number, value: T): T[];
        [n: number]: T;
    }

    Type Parameters

    • T
    Hierarchy

    Indexable

    • [n: number]: T

    Properties

    [unscopables] length

    Methods

    [iterator] at concat entries every filter find findIndex findLast findLastIndex flat flatMap forEach includes indexOf join keys lastIndexOf map reduce reduceRight slice some toLocaleString toReversed toSorted toSpliced toString values with

    Properties

    Readonly[unscopables]

    [unscopables]: {
        [unscopables]?: boolean;
        length?: boolean;
        [iterator]?: any;
        at?: any;
        concat?: any;
        entries?: any;
        every?: any;
        filter?: any;
        find?: any;
        findIndex?: any;
        findLast?: any;
        findLastIndex?: any;
        flat?: any;
        flatMap?: any;
        forEach?: any;
        includes?: any;
        indexOf?: any;
        join?: any;
        keys?: any;
        lastIndexOf?: any;
        map?: any;
        reduce?: any;
        reduceRight?: any;
        slice?: any;
        some?: any;
        toLocaleString?: any;
        toReversed?: any;
        toSorted?: any;
        toSpliced?: any;
        toString?: any;
        values?: any;
        with?: any;
    }

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

    Type declaration

    • Optional Readonly[unscopables]?: boolean

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

    • Optional Readonlylength?: boolean

      Gets the length of the array. This is a number one higher than the highest element defined in an array.

    Readonlylength

    length: number

    Gets the length of the array. This is a number one higher than the highest element defined in an array.

    Methods

    [iterator]

    at

    • at(index): T

    • Returns the item located at the specified index.

      Parameters

      • index: number

        The zero-based index of the desired code unit. A negative index will count back from the last item.

      Returns T

    concat

    • concat(...items): T[]

    • Combines two or more arrays.

      Parameters

      • Rest...items: ConcatArray<T>[]

        Additional items to add to the end of array1.

      Returns T[]

    • concat(...items): T[]

    • Combines two or more arrays.

      Parameters

      • Rest...items: (T | ConcatArray<T>)[]

        Additional items to add to the end of array1.

      Returns T[]

    entries

    • entries(): ArrayIterator<[number, T]>

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

      Returns ArrayIterator<[number, T]>

    every

    • every<S>(predicate, thisArg?): this is readonly S[]

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

      Type Parameters

      • S

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => value is S)

        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, index, array): value is S

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns value is S

      • OptionalthisArg: 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 readonly S[]

    • every(predicate, thisArg?): boolean

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

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => unknown)

        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, index, array): unknown

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns unknown

      • OptionalthisArg: 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

    filter

    • filter<S>(predicate, thisArg?): S[]

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

      Type Parameters

      • S

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => value is S)

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

          • (value, index, array): value is S

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns value is S

      • OptionalthisArg: 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, thisArg?): T[]

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

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => unknown)

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

          • (value, index, array): unknown

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns unknown

      • OptionalthisArg: 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, thisArg?): S

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

      Type Parameters

      • S

      Parameters

      • predicate: ((value: T, index: number, obj: readonly T[]) => value is S)

        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.

          • (value, index, obj): value is S

          • Parameters

            • value: T
            • index: number
            • obj: readonly T[]

            Returns value is S

      • OptionalthisArg: 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

    • find(predicate, thisArg?): T

    • Parameters

      • predicate: ((value: T, index: number, obj: readonly T[]) => unknown)
          • (value, index, obj): unknown

          • Parameters

            • value: T
            • index: number
            • obj: readonly T[]

            Returns unknown

      • OptionalthisArg: any

      Returns T

    findIndex

    • findIndex(predicate, thisArg?): number

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

      Parameters

      • predicate: ((value: T, index: number, obj: readonly T[]) => unknown)

        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, index, obj): unknown

          • Parameters

            • value: T
            • index: number
            • obj: readonly T[]

            Returns unknown

      • OptionalthisArg: 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

    findLast

    • findLast<S>(predicate, thisArg?): S

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

      Type Parameters

      • S

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => value is S)

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

          • (value, index, array): value is S

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns value is S

      • OptionalthisArg: 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

    • findLast(predicate, thisArg?): T

    • Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => unknown)
          • (value, index, array): unknown

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns unknown

      • OptionalthisArg: any

      Returns T

    findLastIndex

    • findLastIndex(predicate, thisArg?): number

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

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => unknown)

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

          • (value, index, array): unknown

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns unknown

      • OptionalthisArg: 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

    flat

    • flat<A, D>(this, depth?): FlatArray<A, D>[]

    • Returns a new array with all sub-array elements concatenated into it recursively up to the specified depth.

      Type Parameters

      • A
      • D extends number = 1

      Parameters

      • this: A
      • Optionaldepth: D

        The maximum recursion depth

      Returns FlatArray<A, D>[]

    flatMap

    • flatMap<U, This>(callback, thisArg?): U[]

    • Calls a defined callback function on each element of an array. Then, flattens the result into a new array. This is identical to a map followed by flat with depth 1.

      Type Parameters

      • U
      • This = undefined

      Parameters

      • callback: ((this: This, value: T, index: number, array: T[]) => U | ReadonlyArray<U>)

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

      • OptionalthisArg: This

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

      Returns U[]

    forEach

    • forEach(callbackfn, thisArg?): void

    • Performs the specified action for each element in an array.

      Parameters

      • callbackfn: ((value: T, index: number, array: readonly T[]) => void)

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

          • (value, index, array): void

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns void

      • OptionalthisArg: 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

    includes

    • includes(searchElement, fromIndex?): boolean

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

      Parameters

      • searchElement: T

        The element to search for.

      • OptionalfromIndex: number

        The position in this array at which to begin searching for searchElement.

      Returns boolean

    indexOf

    • indexOf(searchElement, fromIndex?): number

    • Returns the index of the first occurrence of a value in an array.

      Parameters

      • searchElement: T

        The value to locate in the array.

      • OptionalfromIndex: 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

    • Adds all the elements of an array separated by the specified separator string.

      Parameters

      • Optionalseparator: string

        A string used to separate one element of an array from the next in the resulting String. If omitted, the array elements are separated with a comma.

      Returns string

    keys

    lastIndexOf

    • lastIndexOf(searchElement, fromIndex?): number

    • Returns the index of the last occurrence of a specified value in an array.

      Parameters

      • searchElement: T

        The value to locate in the array.

      • OptionalfromIndex: number

        The array index at which to begin the search. If fromIndex is omitted, the search starts at the last index in the array.

      Returns number

    map

    • map<U>(callbackfn, thisArg?): U[]

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

      Type Parameters

      • U

      Parameters

      • callbackfn: ((value: T, index: number, array: readonly T[]) => U)

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

          • (value, index, array): U

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns U

      • OptionalthisArg: 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[]

    reduce

    • reduce(callbackfn): T

    • 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: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T)

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

          • (previousValue, currentValue, currentIndex, array): T

          • Parameters

            • previousValue: T
            • currentValue: T
            • currentIndex: number
            • array: readonly T[]

            Returns T

      Returns T

    • reduce(callbackfn, initialValue): T

    • Parameters

      • callbackfn: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T)
          • (previousValue, currentValue, currentIndex, array): T

          • Parameters

            • previousValue: T
            • currentValue: T
            • currentIndex: number
            • array: readonly T[]

            Returns T

      • initialValue: T

      Returns T

    • reduce<U>(callbackfn, initialValue): U

    • 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: ((previousValue: U, currentValue: T, currentIndex: number, array: readonly T[]) => U)

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

          • (previousValue, currentValue, currentIndex, array): U

          • Parameters

            • previousValue: U
            • currentValue: T
            • currentIndex: number
            • array: readonly T[]

            Returns U

      • 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): T

    • 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: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T)

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

          • (previousValue, currentValue, currentIndex, array): T

          • Parameters

            • previousValue: T
            • currentValue: T
            • currentIndex: number
            • array: readonly T[]

            Returns T

      Returns T

    • reduceRight(callbackfn, initialValue): T

    • Parameters

      • callbackfn: ((previousValue: T, currentValue: T, currentIndex: number, array: readonly T[]) => T)
          • (previousValue, currentValue, currentIndex, array): T

          • Parameters

            • previousValue: T
            • currentValue: T
            • currentIndex: number
            • array: readonly T[]

            Returns T

      • initialValue: T

      Returns T

    • reduceRight<U>(callbackfn, initialValue): U

    • 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: ((previousValue: U, currentValue: T, currentIndex: number, array: readonly T[]) => U)

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

          • (previousValue, currentValue, currentIndex, array): U

          • Parameters

            • previousValue: U
            • currentValue: T
            • currentIndex: number
            • array: readonly T[]

            Returns U

      • 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

    slice

    • slice(start?, end?): T[]

    • Returns a section of an array.

      Parameters

      • Optionalstart: number

        The beginning of the specified portion of the array.

      • Optionalend: number

        The end of the specified portion of the array. This is exclusive of the element at the index 'end'.

      Returns T[]

    some

    • some(predicate, thisArg?): boolean

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

      Parameters

      • predicate: ((value: T, index: number, array: readonly T[]) => unknown)

        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, index, array): unknown

          • Parameters

            • value: T
            • index: number
            • array: readonly T[]

            Returns unknown

      • OptionalthisArg: 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

    toLocaleString

    • toLocaleString(): string

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

      Returns string

    • toLocaleString(locales, options?): string

    • Parameters

      Returns string

    toReversed

    • toReversed(): T[]

    • Copies the array and returns the copied array with all of its elements reversed.

      Returns T[]

    toSorted

    • toSorted(compareFn?): T[]

    • Copies and sorts the array.

      Parameters

      • OptionalcompareFn: ((a: T, b: T) => number)

        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].toSorted((a, b) => a - b) // [1, 2, 11, 22]
          • (a, b): number

          • Parameters

            Returns number

      Returns T[]

    toSpliced

    • toSpliced(start, deleteCount, ...items): T[]

    • Copies an array and removes elements while, if necessary, inserting new elements in their place, returning the remaining elements.

      Parameters

      • start: number

        The zero-based location in the array from which to start removing elements.

      • deleteCount: number

        The number of elements to remove.

      • Rest...items: T[]

        Elements to insert into the copied array in place of the deleted elements.

      Returns T[]

      A copy of the original array with the remaining elements.

    • toSpliced(start, deleteCount?): T[]

    • Copies an array and removes elements while returning the remaining elements.

      Parameters

      • start: number

        The zero-based location in the array from which to start removing elements.

      • OptionaldeleteCount: number

        The number of elements to remove.

      Returns T[]

      A copy of the original array with the remaining elements.

    toString

    • toString(): string

    • Returns a string representation of an array.

      Returns string

    values

    with

    • with(index, value): T[]

    • Copies an array, then overwrites the value at the provided index with the given value. If the index is negative, then it replaces from the end of the array

      Parameters

      • index: number

        The index of the value to overwrite. If the index is negative, then it replaces from the end of the array.

      • value: T

        The value to insert into the copied array.

      Returns T[]

      A copy of the original array with the inserted value.

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