that "Similar Questions" popup when you're asking a question is smart

smarter than me using the search box at least!

@andre314 In addition to the manual method, you might be interested in this userscript for an automated solution - essentially, you click on the link icon next to any paragraph/... to copy the link to your clipboard

@Nasser - I don't think there is such a function. Associations are supposed to be super easy (and efficient) to add new key/value pairs or modify values.

You could write a function like

ClearAll@modifyThisKeyOnlyIfExists
Attributes[modifyThisKeyOnlyIfExists] = {HoldFirst}
modifyThisKeyOnlyIfExists[assoc_, Rule[key_, value_]] /;
   KeyExistsQ[assoc, key] := Set[assoc[key], value];
modifyThisKeyOnlyIfExists[assoc_,
  Rule[key_, value_]] := (Message[Association::partw, key,
   assoc]; $Failed /; False)