Need help in Javascript for resetting module if user no longer interacts after x seconds.

[jchariot]

I am using a Sonar module on Raspberry Pi to indicate whether someone is in front of the mirror or not. I use MMM-websocket to transfer this information to MagicMirror and it works correctly. Now, when there is nobody in front of the mirror for x seconds, I would like to call a function to reset the module. However, I got an issue on Javascript side:

Currently I have this function for resetting in my module:

userNoLongerInFrontSoReset: function(){
    if (this.resetTimeout != null){
        clearTimeout(this.resetTimeout);
    }

    this.resetTimeout = setTimeout(function(){
        console.log("resetTimeout setTimeout");

        this.myVar = null;
        this.myVar2 = null;
        this.myVar3 = null;

        this.sendNotification("PAGE_CHANGED", 0); 

        this.updateDom();

    }, 3000)
}

I see from the console that resetTimeout setTimeout is being printed out from the code above, but then it got:

Uncaught TypeError: this.sendNotification is not a function at myOwnModule.js:xxx

So this is the problem. All those variables myVar, etc. are not being referred correctly as well as the function sendNotification. How can I set all myVar and call sendNotification from the anonymous function in this case? Or is there a better way to do this?

Thank you,

[A Former User]

@jchariot
Change this;

this.resetTimeout = setTimeout(function(){
 ...
  this.sendNotification("PAGE_CHANGED", 0); 
  this.updateDom();
  ...

to this;

this.resetTimeout = setTimeout(()=>{
 ...
  this.sendNotification("PAGE_CHANGED", 0); 
  this.updateDom();
  ...

Or this;

var module = this
this.resetTimeout = setTimeout(function(){
 ...
  module.sendNotification("PAGE_CHANGED", 0); 
  module.updateDom();
  ...

Inside of function(){...}, this will be function itself, so you cannot access this - referer to module - of upper level.
To avoid, you can use ES6 style anonymous function ()=>{} instead function(){} or assign prior this to another temporal object.

[strawberry 3.141]

@sean or

this.resetTimeout = setTimeout(function(){
 ...
  this.sendNotification("PAGE_CHANGED", 0); 
  this.updateDom();
  ...
}.bind(this));