Question

I need a regular expression in javascript that will accept only positive numbers and decimals. This is what I have but something is wrong — it doesn’t seem to take single positive digits.

/^[-]?[0-9]+[\.]?[0-9]+$/;

For example, 9 will not work. How can I restructure this so if there is at least one positive digit, it will work?

Answer 1

/^[+]?([0-9]+(?:[\.][0-9]*)?|\.[0-9]+)$/

matches

0
+0
1.
1.5
.5

but not

.
1..5
1.2.3
-1

EDIT:

To handle scientific notation (1e6), you might want to do

/^[+]?([0-9]+(?:[\.][0-9]*)?|\.[0-9]+)(?:[eE][+-]?[0-9]+)?$/

If you want strictly positive numbers, no zero, you can do

/^[+]?([1-9][0-9]*(?:[\.][0-9]*)?|0*\.0*[1-9][0-9]*)(?:[eE][+-][0-9]+)?$/