javascript - How do I return the sum of all values in an array? - Stack Overflow

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I am very new to javascript and am having a problem figuring out if I should use return or document.write or both to return the sum of all values in an array called 'amount'. I am supposed to create a function names amountTotal().

The purpose of which is to return the sum of all values in the amount array. Then I am to declare a variable named total, setting its initial value to 0. Then create a for loop that loops through all the values in the amount array.

At each iteration of the loop, add the current value of the array item to the value of the total variable. Finally, after the loop is pleted I need to return the value of the total variable. The largest array value is [34]. This value will be written to a table called Summary

This is what I have written so far.

<script type="text/javascript">
    function amountTotal() {
        var total = 0;
        for (i = 0; i < 35; i++) {
            document.write("<td>" + i + "</td>")
        }
    }
</script>

Am I on the right track?

I am very new to javascript and am having a problem figuring out if I should use return or document.write or both to return the sum of all values in an array called 'amount'. I am supposed to create a function names amountTotal().

The purpose of which is to return the sum of all values in the amount array. Then I am to declare a variable named total, setting its initial value to 0. Then create a for loop that loops through all the values in the amount array.

At each iteration of the loop, add the current value of the array item to the value of the total variable. Finally, after the loop is pleted I need to return the value of the total variable. The largest array value is [34]. This value will be written to a table called Summary

This is what I have written so far.

<script type="text/javascript">
    function amountTotal() {
        var total = 0;
        for (i = 0; i < 35; i++) {
            document.write("<td>" + i + "</td>")
        }
    }
</script>

Am I on the right track?

• javascript
• arrays
• for-loop

Share Improve this question Follow edited Sep 10, 2013 at 14:25 Moazzam Khan 3,17022 gold badges2222 silver badges3737 bronze badges asked Sep 10, 2013 at 14:15 Chris CarterChris Carter 1511 gold badge11 silver badge66 bronze badges 6

• 4 At this stage in your learning process, it's safe to just never even consider using document.write(). Ever. – Pointy Commented Sep 10, 2013 at 14:17
• 1 You should use return according to me. – Arpit Commented Sep 10, 2013 at 14:18
• 1 @Pointy I am also beginner to this language. Can you tell me,why not safe? I am asking out of curiosity. – Arup Rakshit Commented Sep 10, 2013 at 14:21
• So the code would read... return[i]? – Chris Carter Commented Sep 10, 2013 at 14:23
• 1 @ChrisCarter document.write() is not really part of JavaScript. It's a browser operation that's really only useful in a few special cases. – Pointy Commented Sep 10, 2013 at 15:03

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2 Answers 2

Sorted by: Reset to default 4

Return a value from function.

function amountTotal(amount) {
        var total = 0;
        for (i = 0; i < amount.length; ++i) {
             total += amount[i]; // add each element in an array to total
        }
        return total;// return sum of elements in array
}

function sumArray(arr){
    var total = 0;
    arr.forEach(function(element){
        // 'element' in the parenthesis can be any name
        total += element;
    });
    return total;
}

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