javascript float strange behavior [ 976 views ]
Goal: to discover some black hole
Javascript is perfect but… check this small piece of code
for(var i = 0;i < 5; i+=.1){console.log(i);}
[/js]
This is a simple iteration but the result is terrible: (with other arguments like .2, .3 ... the result will be different but bad as well - try)
[js]
0
0.1
0.2
0.30000000000000004
0.4
0.5
0.6
0.7
0.7999999999999999
0.8999999999999999
0.9999999999999999
1.0999999999999999
1.2
1.3
1.4000000000000001
1.5000000000000002
1.6000000000000003
1.7000000000000004
1.8000000000000005
1.9000000000000006
2.0000000000000004
2.1000000000000005
2.2000000000000006
2.3000000000000007
2.400000000000001
2.500000000000001
2.600000000000001
2.700000000000001
2.800000000000001
2.9000000000000012
3.0000000000000013
3.1000000000000014
3.2000000000000015
3.3000000000000016
3.4000000000000017
3.5000000000000018
3.600000000000002
3.700000000000002
3.800000000000002
3.900000000000002
4.000000000000002
4.100000000000001
4.200000000000001
4.300000000000001
4.4
4.5
4.6
4.699999999999999
4.799999999999999
4.899999999999999
4.999999999999998
[/js]
The picture is the same in the main browsers. Nice supprise and we have a simple way to get the correct result. Just use the [js]toFixed()[/js] function.
[js]
for(var i = 0;i < 5; i+=.1){console.log(i.toFixed(1));}
// and the result is correct now:
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
[/js]
Thursday, July 10th, 2014 at 21:58.
Filed under javascript
, tricky.
