Question

188

How to increment number by 0.01 in javascript using a loop?

rated 0 times [ 192] [ 4] / answers: 1 / hits: 26074 / 11 Years ago, thu, october 10, 2013, 12:00:00

Problem

I was trying to build out a list of heights in the console by meteres starting from 1.20m and ending up at 2.50m.

I used this code:

var heights = [];

for ( var i=1.20, l=2.5; i<l; i+=0.01 ){



    heights.push(i);



}



heights = heights.join('n');

If I console.log( heights ) I get:

1.2

1.21

1.22

1.23

...

But then at 1.37 I start getting:

1.37

1.3800000000000001

1.3900000000000001

1.4000000000000001

1.4100000000000001

1.4200000000000002

1.4300000000000002

Questions

What's going on?

How do I fix it?

Demo

var heights = [];

for ( var i=1.20, l=2.5; i<l; i+=0.01 ){



    heights.push(i);



}



var heights = heights.join('n');



document.querySelector('#output').innerText = heights;

<!DOCTYPE html>

<html>

<head>

<meta charset=utf-8 />

<title>JS Bin</title>

</head>

<body>

  <div id=output></div>

</body>

</html>

Answers

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2 Years ago

answered 11 Years ago sonja · Accepted Answer

You are doing this fine. The problem is with the inaccuracy of floating point numbers.

Why are floating point numbers so inaccurate?

If you wish to display this number then use:

heights[i].toFixed(2);

Note that toFixed() returns a string and you will have to convert back to a float (parseFloat()) if you want to perform more numerical operations.