@stdlib/array/base/atnd/lib/main.js

Arrays.

/**
* @license Apache-2.0
*
* Copyright (c) 2024 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

'use strict';

// MAIN //

/**
* Returns an element from an n-dimensional nested array.
*
* @param {ArrayLikeObject} x - input array
* @param {integer} i0 - first dimension index
* @param {...integer} indices - dimension indices
* @returns {*} nested array element
*
* @example
* var x = [ [ 1, 2 ], [ 3, 4 ] ];
*
* var v = atnd( x, 0, 1 );
* // returns 2
*
* v = atnd( x, 1, 0 );
* // returns 3
*
* v = atnd( x, -2, -2 );
* // returns 1
*/
function atnd( x, i0 ) {
	var value;
	var idx;
	var N;
	var i;
	var j;

	idx = [ i0 ];
	for ( i = 2; i < arguments.length; i++ ) {
		idx.push( arguments[ i ] );
	}
	value = x;
	for ( i = 0; i < idx.length; i++ ) {
		j = idx[ i ];
		N = value.length;
		if ( j < 0 ) {
			j += N;
		}
		if ( j < 0 || j >= N ) {
			return;
		}
		value = value[ j ];
	}
	return value;
}


// EXPORTS //

module.exports = atnd;