Read multiple files in Node js and send JSON data

Question

I have multiple files that contains data with time stamps, so I want to read these files in order (and line by line), but I found most of the Node packages use asynchronous method to read files, how can I read each line in order and store all the data in to one string before sending it?

I want to do something like:

    function callbackReadFilesAndSend(res, req){
      var data = ""
      for(int i=0; i<numOfFiles;i++){
     //read lines from files
          data+=...//data from Files[i]
     }
   res.send(data)

}

But I think synchronous methods are bad to use in practice.

Thank you.

Synchronous is only bad if you mix them with asynchronous operation: blog.izs.me/post/59142742143/designing-apis-for-asynchrony — Mμ.
– Mμ., Commented Jun 12, 2017 at 3:27
In this case, if the file data that I'm sending is not too big, can I use readFileSync in a for loop before send it from the server? — Deidara
– Deidara, Commented Jun 12, 2017 at 3:29
Yes you can do that. Although you probably don't want to use data+= to combine all the files together — Mμ.
– Mμ., Commented Jun 12, 2017 at 3:31

Parham Alvani · Accepted Answer · 2017-06-12 03:30:32Z

1

When you want to execute set of known tasks in sequence in node.js you can use something like async.series(tasks[, callback]).

Run the functions in the tasks collection in series, each one running once the previous function has completed.

In other to use async module you must do:

npm install async

and require it in your code:

const async = require('async');

And for this specific purpose (reading the file content), you can use node.js fs synchronous functions like fs.readFileSync(path[, options]).

answered Jun 12, 2017 at 3:30

Parham Alvani

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Shadowfool · Accepted Answer · 2017-06-12 03:26:29Z

0

fs.readFileSync is a sync method for reading files. https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options

answered Jun 12, 2017 at 3:26

Shadowfool

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