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I dont understand javascript array sum

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Jan 09.2018

I dont understand what happend in this code.

<!DOCTYPE html>
<html>
<body>

<p>Click the button to get the sum of the numbers in the array.</p>
<button onclick=”myFunction()”>Try it</button>

<p>Sum of numbers in array: <span id=”demo”></span></p>

<script>
var numbers = [65, 44, 12, 4];

function getSum(total, num) {
return total + num;
}
function myFunction(item) {
document.getElementById(“demo”).innerHTML = numbers.reduce(getSum);
}
</script>

</body>
</html>

What happend in function getSum and what in myFunction? Source is w3schools

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JavaScript

5 Comments(s) ↴

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@rootJan 09.2018 — My suggestion is to read up what the function method reduce() does...

In simple terms, you use the .reduce() on an array and its parameter is a function that is used against the array of element

You could look at it like this, it [B]reduces[/B] the array length by 1 each iteration until it is zero length and quits the function call.

Each time the array is encountered, the array[0] and array[1] are added together (if it exists) and the result is stored in the 1st array element for the next iteration.

Eventually the function completes and out pops your answer.
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@rootJan 09.2018 — Also, when posting code, please use the forum BB Code tags, see my signature for a link and for examples of types.
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@Ashlesha_mishraJan 12.2018 — hi,

reduce() is used for execute each and every value of array from left-to-right.

For sum of array elements, you have to call getSum() until last value of array that is why reduce() is used.

Thanks!
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@Ashlesha_mishraJan 12.2018 — hi,

reduce() is used for execute each and every value of array from left-to-right.

For sum of array elements, you have to call getSum() until last value of array that is why reduce() is used.

You can use it like
[code=html]
var sum = numbers.reduce( function(total, num){
return total + num;
});
[/code]
Thanks!
Copy linkTweet thisAlerts:
@Ashlesha_mishraJan 12.2018 — hi,

reduce() is used for execute each and every value of array from left-to-right.

For sum of array elements, you have to call getSum() until last value of array that is why reduce() is used.

You can use it like
[code=html]
var sum = numbers.reduce( function(total, num){
return total + num;
});
[/code]
Thanks!
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