regex not repeating dot character javascript

Question

I have come up my regex in javascript ^[a-zA-Z0-9.]+([.][a-zA-Z0-9]+)$ which I am trying to filter out string.

No dot character at the begin nor end
dot character can be middle of other Alphabet letter or numbers
If dot character cannot be appear more than twice

These are my expected pass cases

foo.bar
f.o.o
foo.bar.foo
fo.123.321

These are my expected No-pass cases

.foo
.foo.
foo.
foo..bar
.foo.bar

I feel like I am very close(or not at all). How can I filter out dot repeating dot characters? Thanks in advance!

Kerkouch · Accepted Answer · 2018-06-15 00:08:23Z

3

I think that's what you looking for:

/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/

Tests

expected pass cases

/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('foo.bar') // true
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('f.o.o') // true
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('foo.bar.foo') // true
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('fo.123.321') // true

Expected No-pass cases

/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('.foo') // false
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('.foo.') // false
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('foo.') // false
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('foo..bar') // false
/^([a-zA-Z0-9]+\.)+([a-zA-Z0-9]+)$/.test('.foo.bar') // false

answered Jun 15, 2018 at 0:08

Kerkouch

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