functionName is not a function Options

[CharliePrince]

Can anyone tell me how to deal with the error from the code below?

TypeError: this.getDatum is not a function

this.getDatum() runs error-free when call directly (see first call to processThis)

this.getDatum() errors when called on a delay using setTimeout()

CODE

class thisClass {
  constructor() {
      this.getDatum = function() {
          return 777;
      }
  }
  
  processThis() {
    
    let value = this.getDatum();   // (TypeError: this.getDatum is not a function) when called via setTimeout()??
    console.log(`${value} processed error free`);
  }
}



let myObj = new thisClass();

myObj.processThis(); // processes error-free
setTimeout(myObj.processThis, 1000);  // causes (not a function) error in thisClass.processThis
setTimeout(myObj.processThis, 2000);  // causes (not a function) error in thisClass.processThis

[CharliePrince]

I (think) this is what might be happening . . .

after the 1000 ms passes

CODE

setTimeout(myObj.processThis, 1000);

processThis is called. And by that time myObj, as well as thisClass have gone out of scope or something.

Regardless, I've found a way around this issue by just not using a js class

This post has been edited by CharliePrince: Dec 23 2020, 09:34 PM

[Christian J]

There's no method called "getDatum", AFAIK. Maybe you're thinking of "getDate()"?

[pandy]

Just to nitpick, I'd change the grave accents/back-ticks here to quotes.

CODE

console.log(`${value} processed error free`);

And a Merry Christmas to you!

[CharlesEF]

The backticks were added to Javascript, I think its called 'Tagged Template' in ES6. See this page.

[pandy]

Ah! I, obviously, didn't know that. Thanks for the heads up!