@MichMich: Thank’s a lot, I’ve fixed the issue. Result can be reviewed here

First of all a big, very big thank you to Michael Teeuw!!!

MagicMirror is really one of the greatest Raspberry projects followed by ‘pimatic - home automation controller’, another amazing Raspberry project. So far as I know both are developments from Dutchmen.
After studying the documentation and several MM-moduls, I decided to use MagicMirror to setup a central dashboard for my family. Beside customizing of the standard moduls I used the modul ‘MMM-DWD-WarnWeather by LukeSkywalker92’ as a base to create a new modul for retrieving data from my pimatic home controller.
I’m a complete novice to nodejs and all this web stuff, but my programming skill were sufficient to modify the Warnweather module and to integrate the the pimatic socket API.

And voila, here is my dashboard providing now actual information from the internet plus status information from my IoT devices controlled by pimatic.

Special thanks, to those people taken time to document and to publish there solutions.
(As soon as I’ve learned to use git, I will also publish the pimatic modul)

Best regards and a happy new year!

Hi,
I’m at my wit’s end!
Based on module “MMM-FHEM by BenRoe” I’ve created a module to receive event changes from the home automation pimatic. The module works fine. Then I started to write a second modul and can’t get rid of the error:
Cannot read property ‘getElementsByClassName’ of nullt

To isolate the problem I reduced the code to the example from the module development page.

Module.register("HelloWorld",{
    // Default module config.
    defaults: {
        text: "Hello World!"
    },
    
    start: function() {
        var self = this;
        setInterval(function() {
            self.updateDom(); // no speed defined, so it updates instantly.
        }, 1000); //perform every 1000 milliseconds.
    },
    // Override dom generator.
    getDom: function() {
        var wrapper = document.createElement("div");
        wrapper.className = 'MyHelloWorld';
        wrapper.innerHTML = this.config.text;
        return wrapper;
    }
});

Following the console log:

What’ s wrong? I need help from an expert!