JSON to CSV

json-to-csv.js

/*
*	Logan H. Sobczak 6/24/15
*	Converts arbitrary JSON to CSV
*
*	node json-to-csv.js [file1.json, file2.json, ... ]
* outputs to ./csv/file1.csv, ./csv/file2.csv . . .
*/

var fs = require('fs'),
	files = process.argv.slice(2);

fs.exists(__dirname + "/csv", function (exists) {
	// Make an output folder
	if (!exists) fs.mkdirSync(__dirname + "/csv");

	// Iterate over files
	files.forEach(function (file) {
		// Check for json
		if (file.toLowerCase().indexOf("json") == -1) {
			console.err("Are you sure " + file + " is a json file?");
			return;
		}
		fs.readFile(__dirname + "/" + file, function (err, data) {
			if (err) throw (err);
			try {
				var data = JSON.parse(data.toString());
			} catch (err) {
				// Invalid JSON
				throw (err);
			}
			var out = json_to_csv(data, 0);
			fs.writeFileSync(__dirname + "/csv/" + file.split('.')[0] + ".csv", out);
		});
	});

});

function json_to_csv (node, depth) {
	// Array for Array.join rather than concatenating a (potentially) very large string
	var out = [];
	// Iterate over the properties of the node
	for (var prop in node) {
		// Format the depth in the rows
		for (var i = depth; i; i--) {
			out.push(",");
		}
		if (prop) {
			// Wrap numbers in quotes to avoid truncation
			if (Number(prop) || prop == 0) {
				out.push("'");
				out.push(prop);
				out.push("'");
			} else {
				out.push(prop);
			}
			out.push(",");
		}
		if (typeof node[prop] == "object") {
			// New row for new object
			out.push("\n");
			// Recursion + increase depth
			out.push(json_to_csv(node[prop], depth + 1));
		} else {
			// Wrap numbers in quotes to avoid truncation
			if (Number(node[prop])) {
				out.push("'");
				out.push(String(node[prop]));
				out.push("'");
			} else {
				out.push(String(node[prop]));
			}
		}
		out.push("\n");
	}
	// Join text and return
	return out.join("");
}