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JavaScript - find indexes of all occurrences of element in array
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In this article, we would like to show you how to find indexes of all occurrences of element in array using JavaScript.
Quick solution:
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function findIndexes(array, value) {2
var indexes = [];3
for (var i = 0; i < array.length; ++i) {4
if (array[i] === value) {5
indexes.push(i);6
}7
}8
return indexes;9
}10
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// Usage example:13
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var letters = ['a', 'b', 'c', 'b'];15
var result = findIndexes(letters, 'b'); // gets indexes of 'b' occurrences16
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console.log(result); // [1, 3]
In this section, we present an alternative solution using Array reduce() method to get indexes of all occurrences of 'b' element in letters array.
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var letters = ['a', 'b', 'c', 'b'];2
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var result = letters.reduce(function(array, value, index) {4
if (value === 'b') {5
array.push(index);6
}7
return array;8
}, []);9
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console.log(result); // [1, 3]
