Why doesn't my $.getScript work in node?

Question

I am very new to JavaScript. And I am trying to execute a .js file which uses jquery to load other scripts with node. My .js file is called test.js and as follows:

require("jsdom").env("", function(err, window) {
    if (err) {
        console.error(err);
        return;
    }
    var $ = require("jquery")(window);
    $.getScript("./svmjs/lib/svm.js").done(function(){
        console.log("loaded!")
    }).fail(function(){
        console.log("failed!")
    });
})

I am trying to run it on mac with command node test.js , but I get nothing output in the console. What am I doing wrong here? My impression is that with done or fail it will at least output something. But I get nothing. Any ideas?

Answer 1

$.getScript is used to load in scripts on the browser side. In Node.js you have a better tool: require .

Just require your modules directly instead of using jQuery. In fact, it's unlikely you'll need jQuery at all.

Change

$.getScript("./svmjs/lib/svm.js").done(function(){
    console.log("loaded!")
}).fail(function(){
    console.log("failed!")
});

to

require('./svmjs.lib.svm.js');

Answer 2

jQuery will probably not work in Node.js, as it depends heavily on the browser DOM, which is not present in Node.js (there is no window object or other code, native to a browser environment only). Also, you do not need jQuery for loading NPM packages.

Instead, you should do something like this:

1. Navigate to the project directory in a command line. Generate a package.json if you have not done that already by running npm init and following the instructions.
2. Register node-svm , a Node.js-compatible version of SVM, as a dependency by running npm install --save node-svm .
3. Run npm install to download node-svm and its dependencies. They will be installed into the node_modules subdirectory.
4. In index.js or whatever the entry point of your project is (defined in the main property of package.json follow this example and you should be good to go.
5. Run node index.js and check console output.

index.js

var svm = require('node-svm');

var xor = [
    [[0, 0], 0],
    [[0, 1], 1],
    [[1, 0], 1],
    [[1, 1], 0]
];

// initialize a new predictor 
var clf = new svm.CSVC();

clf.train(xor).done(function () {
    // predict things 
    xor.forEach(function(ex){
        var prediction = clf.predictSync(ex[0]);
        console.log('%d XOR %d => %d', ex[0][0], ex[0][1], prediction);
    });
});

Output

0 XOR 0 => 0
0 XOR 1 => 1
1 XOR 0 => 1
1 XOR 1 => 0

Answer 3

I'm assuming that jQuery/$ is undefined . You need to install it into your project using:

npm install jquery --save

After you do that, add var $ = require('jquery'); to the top of your file.

Also, if you're not working in the browser and using strictly Node then you will need to use require instead of jQuery's getScript function. getScript is more suited for browser applications.