Simple Regexp Pattern matching with escape characters

Question

Hopefully a simple one!

I've been trying to get this to work for several hours now but am having no luck, as I'm fairly new to regexp I may be missing something very obvious here and was hoping someone could point me in the right direction. The pattern I want to match is as follows: -

At least 1 or more numbers + "##" + at least 1 or more numbers + "##" + at least 1 or more numbers

so a few examples of valid combinations would be: - 1##2##3 123#123#123 0##0##0

A few invalid combinations would be a##b##c 1## ##1

I've got the following regexp like so: -

[\d+]/#/#[\d+]/#/#[\d+]

And am using it like so (note the double slashes as its inside a string): -

var patt = new RegExp("[\\d+]/#/#[\\d+]/#/#[\\d+]");
if(newFieldValue!=patt){newFieldValue=="no match"}

I also tried these but still nothing: -

if(!patt.text(newFieldValue)){newFieldValue==""}
if(patt.text(newFieldValue)){}else{newFieldValue==""}

But nothing I try is matching, where am I going wrong here?

Any pointers gratefully received, cheers!

Answer 1

1) I can't see any reason to use the RegExp constructor over a RegExp literal for your case. (The former is used primarily where the pattern needs to by dynamic, ie is contributed to by variables.)

2) You don't need a character class if there's only one type of character in it (so \\d+ not [\\d+]

3) You are not actually checking the pattern against the input. You don't apply RegEx by creating an instance of it and using == ; you need to use test() or match() to see if a match is made (the former if you want to check only, not capture)

4) You have == where you mean to assign ( = )

if (!/\d+##\d+##\d+/.test(newFieldValue)) newFieldValue = "no match";

Answer 2

You put + inside the brackets, so you're matching a single character that's either a digit or + , not a sequence of digits. I also don't understand why you have / before each # , your description doesn't mention anything about this character. Use:

var patt = /\d+##\d+##\d+/;

Answer 3

You should use the test method of the pat regex

if (!patt.test(newFieldValue)){ newFieldValue=="no match"; }

once you have a valid regular expression.

Answer 4

Try this regex :

^(?:\d+##){2}\d+$

Demo: http://regex101.com/r/mE8aG7

With the following regex

[\\d+]/#/#[\\d+]/#/#[\\d+]

You would only match things like:

• +/#/#5/#/#+
• +/#/#+/#/#+
• 0/#/#0/#/#0

because the regex engine sees it like on the schema below:

Answer 5

就像是：

((-\\s)?\\d+##)+\\d+