if string.match() doesn't match, why is execution of google apps script cancelled?

问题

if I use the following function within Google Sheets it doesn't return the value "not found". The logs tell me: "Execution cancelled".

This happens at the line:

var found = text.match(re);

If I change searchText to "abc" it works like a charme.

function example()
{
  var text = "abc cba";
  var searchText = "abcd";

  var re = new RegExp(searchText,"g");

  var found = text.match(re);

  if (found === undefined) { 
    return "not found";
  }
  else {
    return found;
  }
} 

Why is the script execution cancelled and how can I prevent this behavior without using the regex twice by using e.g. text.search(re) combined with if before the match() ?

回答1:

Cause:

The return value of string.match ,

An Array whose contents depend on the presence or absence of the global (g) flag, or null if no matches are found.

and

null !== undefined

So, when it's null, the else statement executes and returns null to sheet. The "execution cancelled" is irrelevant and probably from old logsissue

Solution:

Use null to compare return value.

Snippet:

if (found === null) { 

来源：https://stackoverflow.com/questions/60543633/if-string-match-doesnt-match-why-is-execution-of-google-apps-script-cancelle