Answers for "positive lookahead and negative lookahead in js"

8

negative lookbehind javascript

(?=foo)	Lookahead	Asserts that what immediately follows the current position in the string is foo
(?<=foo)	Lookbehind	Asserts that what immediately precedes the current position in the string is foo
(?!foo)	Negative Lookahead	Asserts that what immediately follows the current position in the string is not foo
(?<!foo)	Negative Lookbehind	Asserts that what immediately precedes the current position in the string is not foo
Posted by: Guest on March-08-2021
0

javascript lookahead

Lookaheads are patterns that tell JavaScript to look-ahead in your string
to check for patterns further along. This can be useful when you want to 
search for multiple patterns over the same string.

A positive lookahead will look to make sure the element in the search
pattern is there, but won't actually match it. A positive lookahead is used
as (?=...) where the ... is the required part that is not matched.

On the other hand, a negative lookahead will look to make sure the element
in the search pattern is not there. A negative lookahead is used as (?!...)
where the ... is the pattern that you do not want to be there. The rest of 
the pattern is returned if the negative lookahead part is not present.
Posted by: Guest on January-21-2021

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