How do I include recursive functions in node js from another file

Question

I have the following recursive function saved in a file called helpers.js. When it is loaded into the main app.js file using:

var helpers = require('./helpers');

calling it only works partially. The line:

s+=recurseJSON(o[a]);

doesn't get called so the JSON parsing doesn't recurse into nested levels.

I have also tried the following which still doesn't work:

s+=helpers.recurseJSON(o[a]);

If I move the code below into the main app.js file, the recursion works perfectly, obviously changing

recurseJSON: function(o) {...

to

function recurseJSON(o) {..

Your thoughts are appreciated. Here is the whole code:

module.exports = {
recurseJSON: function(o){
    var s = '';
    for(var a in o){
        if (typeof o[a] == 'object'){
            s+=a+':';
            console.log('JSON>', a, ":");
            s+=recurseJSON(o[a]);  // This line should recurse but doesn't
        }else{
            s+=a+':'+o[a]+'   ';
            console.log('JSON>', a, ":", o[a]);
        }//end if
    }//end for
    return s;
}
};

PS: Credit to Recursively parsing JSON for the original recursive code.

When a function calls itself, that is recursive, not iterative. You likely iterate through each key/value pair in JSON, but in a recursive fashion. — Patrick Roberts
– Patrick Roberts, Commented Jul 1, 2017 at 6:30

Patrick Roberts · Accepted Answer · 2019-01-16 16:59:10Z

1

While leaving the export statement like this:

module.exports = {
  recurseJSON: function(o){
    ...
  }
};

You can call the function recursively using the statement s+=this.recurseJSON(o[a]), but only assuming that the only way you invoke the recurseJSON() function outside the file is

helpers.recurseJSON(obj)

so that recurseJSON() is the calling member of helpers, making the this in recurseJSON() refer to helpers.

If you cannot guarantee this, then the correct way to invoke it, which is more verbose, is

s+=module.exports.recurseJSON(o[a])

Update

Another simpler solution is to just name the function you're exporting:

module.exports = {
  recurseJSON: function recurseJSON(o){
    ...
  }
};

Then you can just use s+=recurseJSON(o[a]) like you had before.

edited Jan 16, 2019 at 16:59

answered Jul 1, 2017 at 6:35

Patrick Roberts

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1 Comment

Rubanraj Ravichandran Over a year ago

s+=module.exports.iterateJSON(o[a]) This worked for me.

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