What does the ?! mean in the following regex expression?
new RegExp('http:\/\/(?!' + location.hostname + ')')
What does the ?! mean in the following regex expression? new RegExp(‘http:\/\/(?!’ + location.hostname
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What does the ?! mean in the following regex expression?
new RegExp('http:\/\/(?!' + location.hostname + ')')
It’s a negative lookahead, which means that for the expression to match, the part within
(?!...)must not match. In this case the regex matcheshttp://only when it is not followed by the current host name (roughly, see Thilo’s comment).