字符串的Javascript正则表达式，后跟确切的字符数

Question

I am looking for a regex for matching the following ids:

path-0
path-1
path-2

And does not match ids with a say bigger number of characters, eg:

path-0-0
path-0-1

Currently I have this chunk of code:

 let array = [ 'path-0', 'path-1', 'path-2', 'path-0-0', 'path-0-1' ]; let reg = /[^path-]{6}/; $.each( array, function(index, value) { if(reg.test(value) ) { console.log(reg.test(value), value); } else { console.error(reg.test(value), value); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

Answer 1

First of all, you want to match beginning of string

^

Then the word "path" followed by a dash

^path-

Then a single character and nothing more (so, end of line)

^path-\d$

As per Arthur's comment, if your intention is to allow ids with more than one digit after "path-" you can specify that you want 1 or more digits by suffixing \\d with + , like this:

^path-\d+$

Answer 2

What you are looking for is a way to check if pattern /-\\d+/ only occurs once. Notice that the symbol + here works to match numbers with more than one digit. You need though to check for string end, represented by $ symbol, the same way ^ represents the beginning of it. The best regex option that will work for you would be:

let reg = /^path-\d+$/;

Answer 3

Brief

As per my original comments...

The reason your pattern [^path-] is not working is because it matches anything not present in the set, so any character except ahpt- (I rearranged the characters so you can better understand what it's saying). Character sets are used when you want to say match anything that is (or is not) in this set .

An example of using a set, for your example, would be ^path-[0-9]$ . This says *match a character between 0 and 9 in the ASCII table, which includes 0123456789 . Another way of defining the same character set is using the shorthand token \\d (which specifies the same characters 0 through 9 ).

The caret symbol ^ used at the start of a set specifies that the set should negate these characters. An example of its use for your example is ^path-[^\\D]$ , which is basically a double-negative specifying anything that is not not a digit (or simply put any digit). Anywhere outside a set (and assuming it's not escaped) ^ means assert position at the start of the string .

Code

^path-\d$

 let array = [ 'path-0', 'path-1', 'path-2', 'path-0-0', 'path-0-1', 'path-12' ]; let reg = /^path-\\d$/; $.each( array, function(index, value) { if(reg.test(value) ) { console.log(reg.test(value), value); } else { console.error(reg.test(value), value); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

If you want to match the possibility of more than 1 digit, you can use the following.

^path-\d+$

 let array = [ 'path-0', 'path-1', 'path-2', 'path-0-0', 'path-0-1', 'path-12' ]; let reg = /^path-\\d+$/; $.each( array, function(index, value) { if(reg.test(value) ) { console.log(reg.test(value), value); } else { console.error(reg.test(value), value); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

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Explanation

• ^ Assert position at the start of the string
• path- Match this literally
• \\d Match any digit
• $ Assert position at the end of the string