0.0.1 • Public • Published


A Node.js module for concatenating JSON files and objects. Use it in Node.js as a plain, old module, in Connect and Express as a middleware and in your terminal as an executable.


$ npm install json-concat --save

To install json-concat onto your command line, you may require passing the -g flag. You may also require some sudo powers to make it work.

$ sudo npm install -g json-concat


As a plain module in your apps

var jsonConcat = require("json-concat");
    src: ["appVars.json", "userVars.json"],
    dest: "./config.json"
}, function (json) {

As a middleware in Connect/Express apps

var express    = require("express"),
    app        = express(),
    jsonConcat = require("json-concat");
    src: ["appVars.json", "userVars.json"],
    dest: __dirname + "/config.json",
    middleware: true

As an executable in the command line

# As simple as this. Output file should be last 
$ json-concat file1.json file2.json ouput.json
# for usage tip, invoke with no args 
$ json-concat


  • The options object passed may have the following keys:
    • src:
      • (String) path pointing to a directory
      • (Array) array of paths pointing to files and/or directories
      • defaults to . (current working directory)
      • Note: if this is a path points to a single file, nothing will be done.
    • dest:
      • (String) path pointing to a file in which the JSON output will be written to
      • (Null) assign null to have no file written to
      • defaults to ./concat.json
    • middleware:
      • (Boolean) whether it is being used as a middleware or not
      • defaults to false
  • The callback receives two arguments:
    • err:
      • An error object if an error does occur
    • json:
      • On Sucess, the concatenated json is passed
      • On error, the json will be an empty string ""
  • In Connect/Express apps, the concatenation is done on server requests
  • It is asynchronous, the Node.js way
  • It is forgiving, keeps going even when an error occurs. For example, a non-existent file or syntax errors in json files
  • It is recursive, following the folders specified. Files with the extension .json are considered. Symbolic links are ignored

Use Cases

In most cases, while building an Express app, you will end up using jade as your view engine. Jade allows you to pass a javascript object, which may be JSON, for external variables. Instead of writing all your variables in one file, you may distribute the variables across directories and concatenate them later into one file. Eventually passing it to the jade engine.

Tests and Performance

Build Status Coverage Status

To see the tests run on each commit, go to the project's Travis page. If interested in the algorithms used, please read the notes at the beginning of src/json-concat.coffee.


  • Include tests (v0.0.0)
  • Allow Synchronous Execution: be called as a function with splats
// Just an example
var json = jsonConcat("appVars.json", "userVars.json", {"name": "@mugo_gocho"});
  • Get the JSON output in a pretty format i.e. with indentations


The MIT License (MIT)

Copyright © 2014-2016 GochoMugo mugo@forfuture.co.ke

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