4 ms·

In a browser console: > const match = /^\/[js]\/(\d+)\/?$/.exec("something") > undefined

• eatingCake 5y ago
  The assignment to match returns undefined. The value of match is null.
  • femto113 5y ago
    To be pedantic the assignment returns null (always returns the rvalue[1]), it's the const statement that produces undefined[2] [1] https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-let-and-const-declarations-runtime-semantics-evaluation https://tc39.es/ecma262/multipage/ecmascript-language-statem... [2] https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-let-and-const-declarations-runtime-semantics-evaluation https://tc39.es/ecma262/multipage/ecmascript-language-statem...
    • cipherboy 5y ago
      And to be even more pedantic, the function works because it is applied on an event listener... When null[1] is evaluated (in the right side of the || of the conditional), it produces a TypeError... which in effect (due to no catch and evaluation continuing in a parent/event-driven scope) is essentially equivalent to an empty return in this specific context. What fun! :-) Edit: apparently as also mentioned https://news.ycombinator.com/item?id=30268412 https://news.ycombinator.com/item?id=30268412
• zeven7 5y ago
  Run just /^\/[js]\/(\d+)\/?$/.exec("something") in the console