How to make function synchronous in Node.js?

1

Hello, everybody!

I have next block in Node.js:

app.post("/api/shorturl/new",  function (req, res, next) {
 
 dns.lookup(res.locals.url, function(err, adresses, family){
    if (err){
      res.locals.urlValid = false;
    } else {
      res.locals.urlValid = true;
    }
  });
  next();
}, 

function (req, res) {
  console.log("URL valid in next? ", res.locals);
    if (res.locals.urlValid) {
      res.json({origin_url: req.body.url});
    }else {    
      res.json({error: "invalid URL"})
    }
});

This code is not working, because app received response from dns.lookup() after app finish chain. So after if I include console.log() in dns.lookup(), it shows after last chain.

So my question is how to order app wait finish of dns.lookup() before handle next chain?

2

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.

Note: Backticks are not single quotes.

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