positive lookbehind browser support
It is a fixed string between two semi-colons, in the comment part of the User Agent. Positive lookbehind: (?<=pattern) matches if pattern matches what For example, in this case, you could split the string into (quoted and /w3schools/i is a regular expression. The browser version is often, but not always, put in the value part of the BrowserName/VersionNumber token in the User Agent String. positive lookahead is a sort of group with parenthesis around it. is a space followed by an optional number one or more quantifier then (? Like in all cases, these strings may change in the future, one should use them only in conjunction with the detection of already released browsers. (4) Here is a regex that works fine in most regex implementations: (?