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* @license Apache-2.0
*
* Copyright (c) 2018 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';
// MODULES //
var isnan = require( '@stdlib/assert/is-nan' );
var isCollection = require( '@stdlib/assert/is-collection' );
var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
var isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
var format = require( '@stdlib/string/format' );
// MAIN //
/**
* Returns the first index at which a given element can be found.
*
* @param {ArrayLike} arr - array-like object
* @param {*} searchElement - element to find
* @param {integer} [fromIndex] - starting index (if negative, the start index is determined relative to last element)
* @throws {TypeError} must provide an array-like object
* @throws {TypeError} third argument must be an integer
* @returns {integer} index or -1
*
* @example
* var arr = [ 4, 3, 2, 1 ];
* var idx = indexOf( arr, 3 );
* // returns 1
*
* @example
* var arr = [ 4, 3, 2, 1 ];
* var idx = indexOf( arr, 5 );
* // returns -1
*
* @example
* // Using a `fromIndex`:
* var arr = [ 1, 2, 3, 4, 5, 2, 6 ];
* var idx = indexOf( arr, 2, 3 );
* // returns 5
*
* @example
* // `fromIndex` which exceeds `array` length:
* var arr = [ 1, 2, 3, 4, 2, 5 ];
* var idx = indexOf( arr, 2, 10 );
* // returns -1
*
* @example
* // Negative `fromIndex`:
* var arr = [ 1, 2, 3, 4, 5, 2, 6, 2 ];
* var idx = indexOf( arr, 2, -4 );
* // returns 5
*
* idx = indexOf( arr, 2, -1 );
* // returns 7
*
* @example
* // Negative `fromIndex` exceeding input `array` length:
* var arr = [ 1, 2, 3, 4, 5, 2, 6 ];
* var idx = indexOf( arr, 2, -10 );
* // returns 1
*
* @example
* // Array-like objects:
* var str = 'bebop';
* var idx = indexOf( str, 'o' );
* // returns 3
*/
function indexOf( arr, searchElement, fromIndex ) {
var len;
var i;
if ( !isCollection( arr ) && !isString( arr ) ) {
throw new TypeError( format( 'invalid argument. First argument must be an array-like object. Value: `%s`.', arr ) );
}
len = arr.length;
if ( len === 0 ) {
return -1;
}
if ( arguments.length === 3 ) {
if ( !isInteger( fromIndex ) ) {
throw new TypeError( format( 'invalid argument. Third argument must be an integer. Value: `%s`.', fromIndex ) );
}
if ( fromIndex >= 0 ) {
if ( fromIndex >= len ) {
return -1;
}
i = fromIndex;
} else {
i = len + fromIndex;
if ( i < 0 ) {
i = 0;
}
}
} else {
i = 0;
}
// Check for `NaN`...
if ( isnan( searchElement ) ) {
for ( ; i < len; i++ ) {
if ( isnan( arr[i] ) ) {
return i;
}
}
} else {
for ( ; i < len; i++ ) {
if ( arr[ i ] === searchElement ) {
return i;
}
}
}
return -1;
}
// EXPORTS //
module.exports = indexOf;
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