CODEWITHSUNDEEP
javascriptregex
ACe
ACe

Reputation: 19

Reg Expression javascript

I need to validate a string to have only letters, digits up to 4, '.', and '_';

Right now I am using 

if(/^[a-zA-Z0-9_.]+$/.test(testString)) 
{
     console.log("Valid string");
}

testString = test.com // (must be valid) 
testString = Te_St.com // (must be valid) 
testString = Te_St1.com // (must be valid) 
testString = Te_St12.com // (must be invalid because has 12 in it and is higher than 4) 
testString = Te_2St1.com // (must be valid) 
testString = Te_24St1.com // (must be invalid because has 24 in it and it higher than 4) 
testString = Te_2$St1.com // (must be invalid because has ilegal character $)

Upvotes: 0

Views: 45

Answers (2)

vks
vks

Reputation: 67968

^(?!.*[1-9]\d)[a-zA-Z0-4_.]+$

Try this.See demo.

https://regex101.com/r/wU7sQ0/12

Upvotes: 1

Casimir et Hippolyte
Casimir et Hippolyte

Reputation: 89557

You can try the pattern below:

/^[a-z._]*(?:[01234](?:[a-z._]+|$))*$/i

but note that this pattern succeeds with an empty string. To prevent this, you can test the string length before or add a lookahead at the start of the pattern:

/^(?=.)[a-z._]*(?:[01234](?:[a-z._]+|$))*$/i

Upvotes: 2

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