Touchstart eventhandler returns event undefined

Question

@touchstart="touchStart(event)"

touchStart(event) {
      console.log(event);
      console.log("touch start");
    }

Why is event returnung undefined?

Answer 1

Events are executed in a different context from which they are defined. Hence we need to bind them to the object which it is attached to. React code will have a lot of these binding statements. Look it up for more details

why do you need to bind a function in a constructor