The first regex given on this page to identify a number fails with:

"1.233e+23",
"1.233"
[download]

but succeeds with:

"1.2e+233"
[download]

Appears to be some sort of problem with multiple digits after a decimal point.

The regex is:

 /^([+-]?)(?=\d|\.\d)\d*(\.\d)?([Ee]([+-]?\d+))?$/
[download]

A slightly modified version which does work for the given cases:

/^([+-]?)(?=\d|\.\d+)\d*(\.\d+)?([Ee]([+-]?\d+))?$/
[download]

The only difference is the extra plus's after each \.

Edited by davido: Added <code> tags.