Why is my Javascript for loop concatenating numbers rather than adding?

Question

I'm trying to write a little snippet where prompts ask the user for 5 numbers and computes the total of the numbers.

So far I have this:

var counter, number, total;

for(counter = 0; counter < 5; counter++) {
  number = parseFloat(prompt("Enter a number:"));
  total += number;
}

document.write("The total is " + total + ".");

However the 'total' returns " " for example, rather than a sum of 15.

How do I fix this?

Thanks in advance!

However the 'total' returns "12345" for example - This is probably when you say total = "" and not the current code in the question. The code in the question prints The total is NaN. — maazadeeb
– maazadeeb, Commented Jul 2, 2017 at 11:59

JV Lobo · Accepted Answer · 2017-07-02 11:49:58Z

3

You should initialize your total var to 0:

var counter, number, total = 0;

for(counter = 0; counter < 5; counter++) {
  number = parseFloat(prompt("Enter a number:"));
  total += number;
}

document.write("The total is " + total + ".");

answered Jul 2, 2017 at 11:49

JV Lobo

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2 Comments

F. Hauri - Give Up GitHub Over a year ago

number is useless: You could write: total += parseFloat(prompt("Enter a number:"));

JV Lobo Over a year ago

agree @F.Hauri but I only copied his code and fixed his main problem. code optimization should be his thing

FKSI · Accepted Answer · 2017-07-02 12:03:11Z

2

You have to set total to 0, like this:

var counter, number, total = 0;

for(counter = 0; counter < 5; counter++) {
  number = parseFloat(prompt("Enter a number:"));
  total += number;
}

document.write("The total is " + total + ".");

edited Jul 2, 2017 at 12:03

answered Jul 2, 2017 at 11:50

FKSI

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1 Comment

F. Hauri - Give Up GitHub Over a year ago

What mean "& co"? First line dont set any other variable than total to 0! 3 variables are declared, but only one is initialised.

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