如何创建可根据其他一些值自动更新的属性？

Question

Suppose I have an object like this with some arbitrary values...

let object = {
  value: 5,
  min: 1,
  max: 100,
  valid: true
}

How could I make it so that the valid property updates automatically if the value property is not within the range? I know I could have made a getter in the object like this...

get valid() {
  if (this.value > this.max || this.value < this.min) {
    return false
  else {
    return true
  }
}

...but this only updates valid when it is accessed. I need valid to always be up to date based on the other values of the object.

It's often that I eventually realize that my entire way of thinking about a problem was wrong. Is this one of those cases? For example, I know that if I use setter functions for updating all three of the other objects I could use them to keep valid up to date, but that seems like the wrong approach.

What should I do?

Answer 1

This is the only way I can think of doing it without getters. It updates the value of valid every time the other properties are updated.

 var obj = { val: 5, minimum: 1, maximum: 100, valid: true, set value(v) { this.val = v; this.updateValid(); }, set min(m) { this.minimum = m; this.updateValid(); }, set max(m) { this.maximum = m; this.updateValid(); }, updateValid : function() { this.valid = (this.val >= this.minimum && this.val <= this.maximum) } } obj.value = -1; console.log(obj);