Error: Cannot find module 'ws'

Hi,
I'm using npm to install sql.js. But when watchify try to bundle the app up, it will throw this error:

 Error: Cannot find module 'ws' from 'C:\my_location\node_modules\sql.js\js'

And in the js file, I only have something like this:

var fs = require('fs');
var SQL = require('sql.js');

var filebuffer = fs.readFileSync('../../db/my_db.sqlite');
var _sqlConn = new SQL.Database(filebuffer);

I'm using a Windows 7 laptop

I really don't know how can i solve this, thanks

Start with the consuming JavaScript entry point and the node_modules/sql.js/js path named in the error; reproduce the npm/watchify bundle and inspect how the ws dependency is resolved. Done means the application bundles without the reported missing-module error.