Javascript checking for float

Question

I've got an app that users input coordinates into.

In the DB and most mapping software they use the decimal notation for lat/lng (eg. 123.1234) rather than the older format: 34N 40' 50.12"

I need to test that a value input into a form is a float, and not a string. But using parseFloat on 34N 40' 50.12" returns 34-- which validates using most tests.

Here's what I'm trying, which is a mashup of a few really clever solutions found here-- but so far I can't get the thing to work properly for all cases. The basic cases I'm testing for are:

123.1234 -- valid
'123.1234' -- valid
34N 40' 50.12" -- invalid
'34N 40' 50.12"' -- invalid
123 --valid
'123' -- valid

Here's a jsfiddle of what I've been trying: http://jsfiddle.net/zfwAj/

isNaN should work to filter out those ones: jsfiddle.net/QYMRe — Joseph Marikle
– Joseph Marikle, Commented Nov 29, 2012 at 22:56
@JosephMarikle You should add that as an answer, it's the most simple way to test that. — bfavaretto
– bfavaretto, Commented Nov 29, 2012 at 23:16

Joseph Marikle · Accepted Answer · 2012-11-29 23:37:30Z

3

Seems I should have posted as an answer

isNaN() should work to filter out those ones jsfiddle.net/QYMRe

answered Nov 29, 2012 at 23:37

Joseph Marikle

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2 Comments

julio Over a year ago

@Joseph-- simple, and elegant-- exactly what I was looking for! Thanks.

Joseph Marikle Over a year ago

@Bruno You're welcome. :) Glad I could help (lol i commented on the wrong spot... it's late)

Bruno · Accepted Answer · 2012-11-29 23:30:37Z

0

Try

/^\d+\.?\d*$/.test( str );

Fiddle here

edited Nov 29, 2012 at 23:30

answered Nov 29, 2012 at 22:58

Bruno

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2 Comments

Ja͢ck Over a year ago

/\D/.test('123.45') // true

Bruno Over a year ago

@Jack Thank you. came up with a different expression :)

ILausuch · Accepted Answer · 2017-05-31 06:52:44Z

0

I suggest this one:

/^-?(\d*\.\d+|\d+(\.\d+)?)$/.test(str)

This accepts negative numbers, and float like (.42)

Fiddle test

answered May 31, 2017 at 6:52

ILausuch

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