只允许字符串中的某个字符。使用Javascript

Question

I have no idea, why this simple code is not working. I am planning to match a string against the allowed pattern. The string should ONLY have az , AZ , 0-9 , _ (underscore), . (dot) , - (hiphen).

Below is code:

var profileIDPattern = /[a-zA-Z0-9_.-]./;
var str = 'Heman%t';
console.log('hemant',profileIDPattern.test(str));

The code logs 'true' for below string, although these string DOES NOT match the pattern.

'Heman%t' -> true
'#Hemant$' -> true

I dont know what is the problem.

Answer 1

Try changing it to this RegExp ( /^[a-zA-Z0-9_.-]*$/ ):

 var profileIDPattern = /^[a-zA-Z0-9_.-]*$/; var str1 = 'Hemant-._67%' var str2 = 'Hemant-._67'; console.log('hemant1',profileIDPattern.test(str1)); console.log('hemant2',profileIDPattern.test(str2)); 

Answer 2

Issues : [a-zA-Z0-9_.-] will match any character inside [] and . will match anything after so basically it will match the mention character and any other character

Use ^ and $ anchor to mention start and end of match and remove .

^[a-zA-Z0-9_.-]+ : starting with any given value inside []

[a-zA-Z0-9_.-]+$ : one or more matches and $ to end the match

 var profileIDPattern = /^[a-zA-Z0-9_.-]+$/; console.log('hemant', profileIDPattern.test('Heman%t')); // no match - console.log('hemant-._', profileIDPattern.test('hemant-._')); // valid match console.log('empty', profileIDPattern.test('')); // no match ,empty