我如何将一个变量分配给另一个变量加上一个常量

Question

What I am looking for is something similar to a get property of C#, but for JS. An example of what I am wanting would look like this:

function myObj(a, b){
     this.a = a;
     this.b = b;
     this.c = a + 5;
}

Let's say I passed in a 5 and a 3. Then a=5, b=3, and c=10. Which is what I want. Now I want to come down into somewhere else and say

obj.a = 10;

So now a=10, b=3, and c=10. This is not what I want, I want c=15 to reflect the change in a. I have been working on this for about 40 minutes and am so frustrated that I cannot seem to get this to work the way I would like. I've tried functions, I've tried what is in the example, and I have tried using the get/set features in ES5 (6? idk when they joined the party)

Anyway, help appreciated, something simple and frustrating. I hate working in JS, lord deliver me from this evil ;)

Answer 1

What I am looking for is something similar to a get property of C#, but for JS.

That would be a get property:

 class MyObj { constructor(a, b) { this.a = a; this.b = b; } get c() { return this.a + 5; } } let obj = new MyObj(5, 3); console.log(obj.c); obj.a = 10; console.log(obj.c);