Solved

JavaScript/REGEX: Decimals Fail Number Validation without Leading 0

Posted on 2014-01-21
3
368 Views
Last Modified: 2014-01-21
This verifies an a string contains a number and only a number:
str.match(/^-?[0-9]\d*(.\d+)?$/g) 

Open in new window

However these numbers fail:
.5
-.5

Open in new window

They pass if there is a 0 before the decimal but I would like it to pass with or without the leading 0.
0
Comment
Question by:hankknight
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
3 Comments
 
LVL 84

Assisted Solution

by:ozo
ozo earned 100 total points
ID: 39796795
You can omit the [0-9]
but then these would also verify as numbers:
-

Open in new window


If you want at least one digit either before or after the decimal point, you might try something like
/^-?(\d+\.?|\.\d)\d*$/
0
 
LVL 82

Assisted Solution

by:leakim971
leakim971 earned 100 total points
ID: 39796801
What not using isNaN ?
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN

isNaN("R")
true
isNaN("1")
false
isNaN("-1")
false
isNaN("-1f")
true
isNaN("1f")
true
0
 
LVL 42

Accepted Solution

by:
David S. earned 300 total points
ID: 39796805
isNaN() would allow empty strings and strings only containing white-space characters though.

This should do it:
/^-?(\d*\.)?\d+$/g

Open in new window

0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

As most anyone who uses or has come across them can attest to, regular expressions (regex) are a complicated bit of magic. Packed so succinctly within their cryptic syntax lies a great deal of power. It's not the "take over the world" kind of power,…
International Data Corporation (IDC) prognosticates that before the current the year gets over disbursing on IT framework products to be sent in cloud environs will be $37.1B.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
The viewer will learn the basics of jQuery, including how to invoke it on a web page. Reference your jQuery libraries: (CODE) Include your new external js/jQuery file: (CODE) Write your first lines of code to setup your site for jQuery.: (CODE)

730 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question