How do I sum total amount of array in loop?

Question

How would I sum the total of amount that is returned in array by using Ajax?

Is there other way to calculate the sum with amount of .000 behind?

Example:

 for (i = 0; i < data.RecordCount; i++) {

 totalBetAmount += parseFloat(data.Records[i].betAmount);

Result: 0.22130000001

welcome to the magic world of floating point numbers ... where nothing is precise — Jaromanda X, Aug 27 '16 at 08:20
Possible duplicate of [How to deal with floating point number precision in JavaScript?](http://stackoverflow.com/questions/1458633/how-to-deal-with-floating-point-number-precision-in-javascript) — Jaromanda X, Aug 27 '16 at 08:20
@MohitTanwani yes , correct i wish to move the decimal points but parseFloat seems not working — Morgan Ng, Aug 27 '16 at 08:21

trincot · Accepted Answer · 2016-08-29T04:40:18.487

This inaccuracies result from the fact that many numbers do not have an exact representation in floating point, which is what JavaScript uses to store numbers.

A pragmatic solution is to round your result to a certain number of decimals after the decimal point, like so:

totalBetAmount = Math.round(totalBetAmount*100000000)/100000000;

Here is a snippet that shows the original number and the rounded number:

// Sample data
var data = {
    Records: [
        { betAmount: 0.0001 },
        { betAmount: 0.0001 },
        { betAmount: 0.0001 },
    ],
    RecordCount: 3
};    

var totalBetAmount = 0;
for (i = 0; i < data.RecordCount; i++) {
   totalBetAmount += parseFloat(data.Records[i].betAmount);
}
console.log('before:', totalBetAmount);
// round of inaccuracies, assuming decimals
totalBetAmount = Math.round(totalBetAmount*100000000)/100000000;
console.log('after:', totalBetAmount);

score 0 · Answer 2 · answered Aug 27 '16 at 08:22

0

Just round the decimal's:

Math.round();

answered Aug 27 '16 at 08:22

Lulceltech

1,662
11
22

No, This is not true! Can you give us an example how does your code work for this question? – Mohammad Kermani Aug 27 '16 at 09:14
Had you read the comments to the original question you'd understand what he actually meant =.= – Lulceltech Aug 28 '16 at 08:31

score 0 · Answer 3 · answered Aug 27 '16 at 08:41

Try like this.

//this will be total sum of all numbers
var totalSum = (data.Records || []).reduce(function(total, num){
    return parseFloat(total) + parseFloat(num);
});
//now you can do what you want using ParseInt or toFixed...

//convert to INT
totalSum = parseInt(totalSum);

//leave just 2 numbers after decimal like 1.12
totalSum = totalSum.toFixed(2);

Hope this helps.

score 0 · Answer 4 · answered Aug 27 '16 at 09:21

If you use ES6 (ECMAScript 2015), you can use the reduce function (Great video tutorial to learn the reduce)

Here is a simple example:

var yourArray = [50, 60, 70, 100, 20]
var sum = yourArray.reduce((a, b) => a + b, 0);
console.log(sum); //Returns: 300

score 0 · Answer 5 · answered Aug 27 '16 at 12:37

0

I'm not familiar with Ajax but this might be helpul :

var arr = [5.33655,6.6655,9.554];
var sum = 0;
for (var i = 0 ; i < arr.length ; i++) {
  sum += arr[i] 
};
console.log(sum.toFixed(3));

answered Aug 27 '16 at 12:37

Karan Dhir

731
1
6
24

How do I sum total amount of array in loop?

5 Answers5