I'm building an application that uses Java inside Node.js. I made a Function to check the Java version:

function javaversion() {
    var spawn = require('child_process').spawn('java', ['-version']);
    spawn.stderr.on('data', function(data) {
        data = data.toString().split('\n')[0];
        var javaVersion = new RegExp('java version').test(data) ? data.split(' ')[2].replace(/"/g, '') : false;
        if (javaVersion != false) {
            // TODO: We have Java installed
        } else {
            // TODO: No Java installed
        }
    });
}

But for systems that Java is not installed, Node.js is throwing ENOENT error, because the module "child_process" just can't spawn the process. How can I verify if Java is installed from Node.js?

I appreciate your help!

I'm building an application that uses Java inside Node.js. I made a Function to check the Java version:

function javaversion() {
    var spawn = require('child_process').spawn('java', ['-version']);
    spawn.stderr.on('data', function(data) {
        data = data.toString().split('\n')[0];
        var javaVersion = new RegExp('java version').test(data) ? data.split(' ')[2].replace(/"/g, '') : false;
        if (javaVersion != false) {
            // TODO: We have Java installed
        } else {
            // TODO: No Java installed
        }
    });
}

But for systems that Java is not installed, Node.js is throwing ENOENT error, because the module "child_process" just can't spawn the process. How can I verify if Java is installed from Node.js?

I appreciate your help!

• java
• javascript
• node.js

Share Improve this question Follow asked Nov 1, 2013 at 20:01 FormigaFormiga 11111 silver badge1212 bronze badges 3

• have you considered checking for an environment variable like classpath or ...? And then looking for the binary? – WiredPrairie Commented Nov 1, 2013 at 21:42
• @WiredPrairie, Yes, I considered, but it is not a good idea to all systems. For example, in OS X 10.8, CLASSPATH is not set. I solved the problem handling the error of not spawning the process, like Sudsy suggested. Thank you. – Formiga Commented Nov 2, 2013 at 0:09
• I've got Java installed (per the Windows installer), but it's not in the path, so this method fails pletely. So, doesn't really seem like a good solution for "all systems." – WiredPrairie Commented Nov 2, 2013 at 1:40

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1 Answer 1

Sorted by: Reset to default 7

What about this?

function javaversion(callback) {
    var spawn = require('child_process').spawn('java', ['-version']);
    spawn.on('error', function(err){
        return callback(err, null);
    })
    spawn.stderr.on('data', function(data) {
        data = data.toString().split('\n')[0];
        var javaVersion = new RegExp('java version').test(data) ? data.split(' ')[2].replace(/"/g, '') : false;
        if (javaVersion != false) {
            // TODO: We have Java installed
            return callback(null, javaVersion);
        } else {
            // TODO: No Java installed

        }
    });
}

javaversion(function(err,version){
    console.log("Version is " + version);
})