feat: improve index.d.ts for nanmax-by

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---

Author: DivyanshuVortex

lib/node_modules/@stdlib/stats/base/ndarray/nanmax-by/docs/types/index.d.ts

@@ -22,16 +22,49 @@
 
 import { typedndarray } from '@stdlib/types/ndarray';
 
-type Nullary<U> = ( this: U ) => number | void;
-type Unary<T, U> = ( this: U, value: T ) => number | void;
-type Binary<T, U> = ( this: U, value: T, index: number ) => number | void;
-type Ternary<T, U> = ( this: U, value: T, index: number, array: typedndarray<T> ) => number | void;
+/**
+* Callback function applied to each element of an ndarray.
+*
+* @returns result
+*/
+type Nullary<ThisArg> = ( this: ThisArg ) => number | void;
+
+/**
+* Callback function applied to each element of an ndarray.
+*
+* @param value - current array element
+* @returns result
+*/
+type Unary<T, ThisArg> = ( this: ThisArg, value: T ) => number | void;
 
-type Callback<T, U> =
-	| Nullary<U>
-	| Unary<T, U>
-	| Binary<T, U>
-	| Ternary<T, U>;
+/**
+* Callback function applied to each element of an ndarray.
+*
+* @param value - current array element
+* @param index - current array element index
+* @returns result
+*/
+type Binary<T, ThisArg> = ( this: ThisArg, value: T, index: number ) => number | void;
+
+/**
+* Callback function applied to each element of an ndarray.
+*
+* @param value - current array element
+* @param index - current array element index
+* @param array - input ndarray
+* @returns result
+*/
+type Ternary<T, U, ThisArg> = ( this: ThisArg, value: T, index: number, array: U ) => number | void;
+
+/**
+* Callback function applied to each element of an ndarray.
+*
+* @param value - current array element
+* @param index - current array element index
+* @param array - input ndarray
+* @returns result
+*/
+type Callback<T, U, ThisArg> = Nullary<ThisArg> | Unary<T, ThisArg> | Binary<T, ThisArg> | Ternary<T, U, ThisArg>;
 
 /**
 * Computes the maximum value of a one-dimensional ndarray via a callback function, ignoring `NaN` values.
@@ -54,9 +87,9 @@ type Callback<T, U> =
 * var v = nanmaxBy( [ x ], clbk );
 * // returns 8.0
 */
-type Routine =
-	<T = unknown, U = unknown>( arrays: [ typedndarray<T> ], clbk: Callback<T, U>, thisArg?: ThisParameterType<Callback<T, U>> ) => number;
+declare function nanmaxBy<T = unknown, U extends typedndarray<T> = typedndarray<T>, ThisArg = unknown>( arrays: [ U ], clbk: Callback<T, U, ThisArg>, thisArg?: ThisParameterType<Callback<T, U, ThisArg>> ): number;
+
 
-declare var nanmaxBy: Routine;
+// EXPORTS //
 
 export = nanmaxBy;