Simple regex not working in Javascript

Question

My regex is next

/^(\.\w*)|(\d*\.?\d*)$/

it should works well for float numbers (123.23, 12., .56) and any words that starts from dot.
I was confused when
/^(\.\w*)|(\d*\.?\d*)$/.test("qweasdzxc"); // return true
but without OR:

/^(\.\w*)$/.test("qweasdzxc"); // return false   
/^(\d*\.?\d*)$/.test("qweasdzxc"); // return false

On RegexPal all works well

The equivalent expressions without OR are ^(\.\w*) and (\d*\.?\d*)$ and the latter is true. — Felix Kling
– Felix Kling, Commented Mar 18, 2013 at 12:13

Arun P Johny · Accepted Answer · 2013-03-18 12:21:46Z

2

It should be

/^((\.\w*)|(\d*\.?\d*))$/

You need to wrap both the OR conditions within another (..).

Other wise it is interpreted as ^(\.\w*) or (\d*\.?\d*)$ instead of ^ and ( (\.\w*) or (\d*\.?\d*) ) and $.

Demo: Fiddle

edited Mar 18, 2013 at 12:21

answered Mar 18, 2013 at 12:13

Arun P Johny

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GoT · Accepted Answer · 2013-03-18 12:13:01Z

1

Try this

/^((\.\w*)|(\d*\.?\d*))$/.test("qweasdzxc"); // false
/^((\.\w*)|(\d*\.?\d*))$/.test(".5"); // true

You must encapsulate regex condition (A|B).

answered Mar 18, 2013 at 12:13

GoT

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