133 lines
3.1 KiB
JavaScript
133 lines
3.1 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var isnan = require( '@stdlib/assert/is-nan' );
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var isCollection = require( '@stdlib/assert/is-collection' );
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var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
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var isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
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// MAIN //
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/**
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* Returns the first index at which a given element can be found.
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*
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* @param {ArrayLike} arr - array-like object
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* @param {*} searchElement - element to find
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* @param {integer} [fromIndex] - starting index (if negative, the start index is determined relative to last element)
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* @throws {TypeError} must provide an array-like object
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* @throws {TypeError} `fromIndex` must be an integer
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* @returns {integer} index or -1
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*
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* @example
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* var arr = [ 4, 3, 2, 1 ];
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* var idx = indexOf( arr, 3 );
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* // returns 1
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*
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* @example
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* var arr = [ 4, 3, 2, 1 ];
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* var idx = indexOf( arr, 5 );
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* // returns -1
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*
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* @example
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* // Using a `fromIndex`:
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* var arr = [ 1, 2, 3, 4, 5, 2, 6 ];
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* var idx = indexOf( arr, 2, 3 );
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* // returns 5
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*
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* @example
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* // `fromIndex` which exceeds `array` length:
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* var arr = [ 1, 2, 3, 4, 2, 5 ];
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* var idx = indexOf( arr, 2, 10 );
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* // returns -1
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*
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* @example
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* // Negative `fromIndex`:
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* var arr = [ 1, 2, 3, 4, 5, 2, 6, 2 ];
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* var idx = indexOf( arr, 2, -4 );
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* // returns 5
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*
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* idx = indexOf( arr, 2, -1 );
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* // returns 7
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*
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* @example
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* // Negative `fromIndex` exceeding input `array` length:
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* var arr = [ 1, 2, 3, 4, 5, 2, 6 ];
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* var idx = indexOf( arr, 2, -10 );
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* // returns 1
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*
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* @example
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* // Array-like objects:
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* var str = 'bebop';
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* var idx = indexOf( str, 'o' );
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* // returns 3
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*/
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function indexOf( arr, searchElement, fromIndex ) {
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var len;
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var i;
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if ( !isCollection( arr ) && !isString( arr ) ) {
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throw new TypeError( 'invalid argument. First argument must be an array-like object. Value: `' + arr + '`.' );
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}
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len = arr.length;
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if ( len === 0 ) {
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return -1;
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}
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if ( arguments.length === 3 ) {
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if ( !isInteger( fromIndex ) ) {
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throw new TypeError( 'invalid argument. `fromIndex` must be an integer. Value: `' + fromIndex + '`.' );
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}
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if ( fromIndex >= 0 ) {
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if ( fromIndex >= len ) {
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return -1;
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}
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i = fromIndex;
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} else {
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i = len + fromIndex;
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if ( i < 0 ) {
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i = 0;
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}
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}
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} else {
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i = 0;
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}
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// Check for `NaN`...
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if ( isnan( searchElement ) ) {
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for ( ; i < len; i++ ) {
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if ( isnan( arr[i] ) ) {
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return i;
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}
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}
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} else {
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for ( ; i < len; i++ ) {
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if ( arr[ i ] === searchElement ) {
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return i;
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}
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}
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}
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return -1;
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}
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// EXPORTS //
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module.exports = indexOf;
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