Regular Expression to accept only positive numbers and decimals

You can try this -

^\d{0,10}(\.\d{0,2})?$

Also one cool site to test as well as to get description of your own regular expressions https://regex101.com/

/^[+]?([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]+)?$/

There are few different ways to do this depending on your need:

/^[0-9.]+$/ matches 1 and 1.1 but not -1

/^[0-9]+\.[0-9]+$/ matches 1.1 but not 1 or -1

Generally, I recommend using a simple regExp reference guide like http://www.regular-expressions.info/ for building expressions, and then test them using javascript right your browser console:

"123.45".match(/^[0-9.]+$/)