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c47aca0da3
* Better Array.prototype.flat definition * Use more meaningful names * Rename 'Flat' to 'FlatArray'
66 lines
2.3 KiB
TypeScript
66 lines
2.3 KiB
TypeScript
type FlatArray<Arr, Depth extends number> = {
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"done": Arr,
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"recur": Arr extends ReadonlyArray<infer InnerArr>
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? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][Depth]>
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: Arr
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}[Depth extends -1 ? "done" : "recur"];
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interface ReadonlyArray<T> {
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/**
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* Calls a defined callback function on each element of an array. Then, flattens the result into
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* a new array.
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* This is identical to a map followed by flat with depth 1.
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*
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* @param callback A function that accepts up to three arguments. The flatMap method calls the
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* callback function one time for each element in the array.
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* @param thisArg An object to which the this keyword can refer in the callback function. If
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* thisArg is omitted, undefined is used as the this value.
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*/
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flatMap<U, This = undefined> (
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callback: (this: This, value: T, index: number, array: T[]) => U | ReadonlyArray<U>,
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thisArg?: This
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): U[]
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/**
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* Returns a new array with all sub-array elements concatenated into it recursively up to the
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* specified depth.
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*
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* @param depth The maximum recursion depth
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*/
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flat<A, D extends number = 1>(
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this: A,
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depth?: D
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): FlatArray<A, D>[]
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}
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interface Array<T> {
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/**
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* Calls a defined callback function on each element of an array. Then, flattens the result into
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* a new array.
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* This is identical to a map followed by flat with depth 1.
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*
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* @param callback A function that accepts up to three arguments. The flatMap method calls the
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* callback function one time for each element in the array.
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* @param thisArg An object to which the this keyword can refer in the callback function. If
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* thisArg is omitted, undefined is used as the this value.
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*/
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flatMap<U, This = undefined> (
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callback: (this: This, value: T, index: number, array: T[]) => U | ReadonlyArray<U>,
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thisArg?: This
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): U[]
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/**
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* Returns a new array with all sub-array elements concatenated into it recursively up to the
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* specified depth.
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*
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* @param depth The maximum recursion depth
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*/
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flat<A, D extends number = 1>(
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this: A,
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depth?: D
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): FlatArray<A, D>[]
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}
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