使用点符号访问 class 或 object 之外的 object 属性？

Question

So this may be simple and I'm probably understanding this wrong..

I have created both classes and functions in my code that have the parameters of x, y and z as such..

class Example {
constructor(x, y, z) {
    this.x = x;
    this.y = y;
    this.z = z;
...}
Example(123, 456, 789);

I have seen code being used such as this -

if (Math.hypot(ship.x - enemy.x, ship.y - enemy.y [....] 

But i cannot access any of the values outside of the class using anything such as..

console.log(Example.x);
if (Example.x > 1){ console.log('something here');

It always just says undefined or just doesnt work. I have tried using this dot notation on functions and classes but nothing works, I can only log the values if i place the console log inside the class with just (x) for example.

Please could someone elaborate on how I would be able to use the example of ship.x - enemy.x to access those properties.

Thanks

Answer 1

You should use the keyword new to create an instance of your your class soo the constructor gets executed. Then you can use the dot notation to access it for example:

               class Example {
               constructor(x, y, z) {
                this.x = x;
                this.y = y;
                this.z = z;
                }
                var exp = new Example(123, 465, 789);
                 console.log(exp.x);