javascript - Matching multiple occurrences of consecutive characters from a set - Stack Overflow

admin管理员组

文章数量:1435859

I am trying to match 3 or more consecutive occurrences of one/more special characters from a set in a string.

my js:
var exp = new RegExp("^[\^\$\*%#`!]{3}+$"); 
return !exp.test(myString);

Not working. Any help will be appreciated.

this i$ a te$t: false
th!$ a te$t: false

th!s is a ^%* test: true 
as it has 3 consecutive characters from my set '^%*'

this is a ^%^&%&%& test: true
as it has 3 or more consecutive characters from my set

EDIT:

I corrected the regex. This in JavaScript

var exp = new RegExp("[\^$%#`]{3}"); return exp.test(myString);

Why it is saying this is a match? %^ $^ $^ $^ &^ &^ & %

This input has 2 characters at most and has space in between.

I am trying to match 3 or more consecutive occurrences of one/more special characters from a set in a string.

my js:
var exp = new RegExp("^[\^\$\*%#`!]{3}+$"); 
return !exp.test(myString);

Not working. Any help will be appreciated.

this i$ a te$t: false
th!$ a te$t: false

th!s is a ^%* test: true 
as it has 3 consecutive characters from my set '^%*'

this is a ^%^&%&%& test: true
as it has 3 or more consecutive characters from my set

EDIT:

I corrected the regex. This in JavaScript

var exp = new RegExp("[\^$%#`]{3}"); return exp.test(myString);

Why it is saying this is a match? %^ $^ $^ $^ &^ &^ & %

This input has 2 characters at most and has space in between.

• javascript
• regex

Share Improve this question Follow edited Mar 29, 2012 at 18:44 kheya asked Mar 29, 2012 at 18:29 kheyakheya 7,6212020 gold badges7979 silver badges115115 bronze badges 2

• your regex is invalid, you can't have the + after the {3} that's like saying "I want it exactly 3 times, but also 1 or more times is acceptable." – Robbie Commented Mar 29, 2012 at 18:35
• in your update, that is matching because you have a space in the character set.... check my answer below... i've tested it and it seems to work – Robbie Commented Mar 29, 2012 at 18:50

Add a ment  | 

4 Answers 4

Sorted by: Reset to default 3

new RegExp("[\^\$\*%#`!]{3}");

The leading ^ indicated that the pattern must start at the beginning of the string. The trailing $ indicated that the pattern must end at the end of the string. The bination of these would indicate that the only valid match is a string consisting only of your special characters.

Finally, the + isn't necessary, at soon as you find the first 3 consecutive special characters, you're done; that it can match 5 is irrelevant.

I guess you want

/[\^$*%#`!]{3,}/
== new RegExp("[\\^$*%#`!]{3,}")

Your string should have a occurence of these characters, not consist out of them. Also, .{3}+ seems odd to me.

---

EDIT (to answer your extended question):

Also, if you want to escape the ^ with a backslash, you will have to escape the backslash itself in the string for your RegExp constructor. Your new RegExp("[\^$%#']{3}") equals /[^$%#']{3}]/, which matches the sequence "^ &".

You're looking for only 3 characters between the ^ and $ of the string. You'll want to pad on either end with .*? (or just leave out the ^ and $).

http://regexpal./ is always helpful.

Try this:

Regex:

/[\^$*%#`!]{3,}/

Javascript tests:

var result = new RegExp(/[\^$*%#`!]{3,}/).test("%^ $^ $^ $^ &^ &^ & %"); 
// result now "false"
new RegExp(/[\^$*%#`!]{3,}/).test("th!s is a ^%* test"); 
// result is now "true"

I've removed the invalid + and some unnecessary escape chars. Oh, and as suggested by the other users, the Anchors ^$ are not needed .

You could however wrap the regex in \b tags if you wanted to limit the matches to word boundaries (so that it doesn't match in the middle of a set of characters - only if the set is on its own)

本文标签： javascriptMatching multiple occurrences of consecutive characters from a setStack Overflow