How to get argument from inside an inner function in a node.js route to below scope

Question

I obtained the code below from the NPM package node-dir, The code works fine as it reads a directory and than reads each file in the directory and spits it back out to the console. What I really want is for it to be sent with JSON.stringify so I can than perform an ajax or $.getJSON call to render it to the UI so I can build reports from the data.

I get where the issue is, the files argument is inside of the second functions scope. So when I try to perform the req.send with files it says files is undefined. If I try to put req.send inside of the function it will say req is not defined, or if I pass in req as an argument it will say req.send is not a function because the function is stored with in router.get.

Im hoping for a simple solution with the current code or is there a better approach? I believe it may have something to do with .apply() or possibly some kind of callback or promise maybe? Sorry im still a noob with this kind of functional programming.

router.get("/api/all/reports", (req, res) => {
     const pathToDir = path.resolve(__dirname, "../../", "automation_projects/fcsf/results/");
    dir.readFiles(pathToDir,
       function(err, content, next) {
           if (err) throw err;
           console.log('content:', content);
           next();
          res.send(JSON.stringify(content));
       },
       function(err, files){
           if (err) throw err;
       });

    });

Answer 1

router.get("/api/all/reports", (req, res) => {
     let fileContent = "";
     const pathToDir = path.resolve(__dirname, "../../", "automation_projects/fcsf/results/");
    dir.readFiles(pathToDir,
       function(err, content, next) {
           if (err) throw err;
           console.log('content:', content);
           fileContent += content; 
           next()
       },
       function(err, files){
           if (err) throw err;
           res.send(JSON.stringify(fileContent));
       });

    });

Please let me know if it's working. I think it should be res.send or res.json (not mandatory)

please be careful with large file content. You need to use res.pipe or any streaming functionality for that