I'll preface this question by mentioning that while I'm far from a regular expressions guru, they are not completely foreign to me. Building a regular expression to search for a pattern inside a particular string generally isn't a problem for me, but I have a (maybe?) unique situation.
I have a set of values, say:
028938
DEF567987
390987.456
GHI345928.039
I want to match a certain set of strings, such as:
In the above examples, the first and third values should be matched.
I'm using the regular expressions:
[0-9]{6} [0-9]{6}.[0-9]{3}
Unfortunately, since all the above examples contain the specified pattern, all values are matched. This is not my intention.
So my question, in a nutshell, is how to write a regular expression that matches a string exactly and completely, with no additional characters to the right or left of the matched pattern? Is there a term for this type of matching? (Google was no help.) TIA
We can match an exact string with JavaScript by using the JavaScript string's match method with a regex pattern that has the delimiters for the start and end of the string with the exact word in between those.
Use the test() method to check if a regular expression matches an entire string, e.g. /^hello$/. test(str) . The caret ^ and dollar sign $ match the beginning and end of the string. The test method returns true if the regex matches the entire string, and false otherwise.
Match any specific character in a setUse square brackets [] to match any characters in a set. Use \w to match any single alphanumeric character: 0-9 , a-z , A-Z , and _ (underscore). Use \d to match any single digit. Use \s to match any single whitespace character.
use ^
and $
to match the start and end of your string
^[0-9]{6}$ ^[0-9]{6}\.[0-9]{3}$
Reference: http://www.regular-expressions.info/anchors.html
Also, as noted by Mikael Svenson, you can use the word boundary \b
if you are searching for this pattern in a larger chunk of text.
Reference: http://www.regular-expressions.info/wordboundaries.html
You could also write both those regexes in one shot
^\d{6}(\.\d{3})?$
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