Explanation
1. The first assertion is to tell JavaScript to search forward in the string for a matching pattern. Might be useful if you want to search for multiple matching patterns on the same string.
2. There are two types of lookahead assertions: positive lookahead assertions and negative lookahead assertions.
Example
let quit = "qu"; let noquit = "qt"; let quRegex= /q(?=u)/; let qRegex = /q(?!u)/; quit.match(quRegex); noquit.match(qRegex);
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