JavaScript Array reduce() Method
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JavaScript Array reduce() Method
The reduce() method executes a provided function on each element of the array, resulting in a single output value.
Note: This method does not alter the original array.
Example
HTML Online Editor
<!DOCTYPE html>
<html>
<body>
<p>Sum of Elements in myNumber is<p>
<script>
var myNumber = [1, 2, 3, 4, 5, 6, 7];
function sumUp(accumulator, currentValue, currentIndex, arr) {
return num = accumulator + currentValue;
}
document.write(myNumber.reduce(sumUp));
</script>
</body>
</html>
Syntax
Array.reduce(function(accumulator, currentValue, currentIndex, arr), initialValue);
//or
Array.reduce(functionName);
Parameter Values
| Value | Type | Explanation |
|---|---|---|
| function(accumulator, currentValue, currentIndex, arr) | Required | Function to execute on each element in the array, taking four arguments. accumulator - The accumulator accumulates the callback's return value i.e.) The initialValue, or the previously returned value of the function. Required. currentValue - Specifies the current element being processed in the array. Required. currentIndex - Specifies the index of the current element being processed in the array. Optional. arr - Specifies the whole array. Optional. |
| initialValue | Optional | Specifies a value against which each element in an array is tested. |
Example
HTML Online Editor
<!DOCTYPE html>
<html>
<body>
<p>Sum of Elements in myNumber is<p>
<script>
var myNumber = [1, 2, 3, 4, 5, 6, 7];
function sumUp(accumulator, currentValue, currentIndex, arr) {
return num = accumulator + currentValue;
}
document.write(myNumber.reduce(sumUp, 100));
</script>
</body>
</html>
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