var jsonfile = require('jsonfile'); var util = require('util'); var file = '../src/imageprocessor/project.json'; var buildNumber = process.env.APPVEYOR_BUILD_NUMBER; jsonfile.readFile(file, function (err, project) { project.version = buildNumber; jsonfile.writeFile(file, project, {spaces: 2}, function(err) { console.error(err); }); })