Match a string(input text from user) with regular expression

Question

I have a requirement where there is a customet name text box and the user able to input customer name to search customer. And the condition is user can add do wild card search putting * either infront or after the customer name. And the customer name should be minimum three characters long. I am using Regex to validate the user entry. Now in case the input is like "*aaa*" .. I am validate this type of input using the following regex :

[*]{1}([az]|[AZ]|[0-9]){3,}[*]{1}

The code is like below:

  var str = "*aaa*"; var patt = new RegExp("[*]{1}([az]|[AZ]|[0-9]){3,}[*]{1}"); var res = patt.test(str); alert(res); 

  var str = "*aaa***"; var patt = new RegExp("[*]{1}([az]|[AZ]|[0-9]){3,}[*]{1}"); var res = patt.test(str); alert(res); 

  var str = "*aaa*$$$$"; var patt = new RegExp("[*]{1}([az]|[AZ]|[0-9]){3,}[*]{1}"); var res = patt.test(str); alert(res); 

Now for the input "*aaa*" res is coming true. But for this type of inputs also "*aaa**", "*aaa*$" its comimg true. And this expected as these expressions also contains the part( *aaa*) which satisfies the regex.But these inputs("*aaa**", *aaa*$** etc. ) are wrong.

Please let me know where I am doing wrong ? is there any issue with the regex or the way checking is wrong ?

Answer 1

^(?:[*]([a-z]|[A-Z]|[0-9]){3,}[*])$

Use anchors ^$ to disable partial matching.See demo.

https://regex101.com/r/tS1hW2/17

Answer 2

The string *aaa*$$$ contains a segment of *aaa* , so it will yield true ; to match against the whole string you need to add anchors on both sides. The $ and ^ anchors assert the start and end of the subject respectively.

Also, you can simply the expression greatly by using a character class trick. The \\w is comprised of [0-9a-zA-Z_] , and we only don't want the underscore, so we can use a negative character class with the opposite of \\w (which is \\W ) and an underscore; I agree, it takes some mental power ;-)

 var str = "*aaa*$"; var patt = /^\\*[^\\W_]{3,}\\*$/; var res = patt.test(str); alert(res); // false 

Alternatively, you can merge all your character classes together into one like so:

[A-Za-z0-9]