Watch, apply same code to 2 different functions

Question

I don't know if the title is the best to describe my problem, but was the best way to introduce my daubt.

So basically i have this:

 watch: {
        valueYou: function(val){
            if(val < 15){
                this.progressYou.backgroundColor = "red";
            }
            else if(val < 50){
                this.progressYou.backgroundColor = "orange";
            }
            else{
                this.progressYou.backgroundColor = "green";
            }
        },
        valueMonster: function(val){
             if(val < 15){
                this.progressMonster.backgroundColor = "red";
            }
            else if(val < 50){
                this.progressMonster.backgroundColor = "orange";
            }
            else{
                this.progressMonster.backgroundColor = "green";
            }
        }
    }

as you can see, there are just 1 think that changes, that is the this.progressMonster and this.progressYou, i really want to optimize this into a function and really need to know how to that, how can i pass trough a function the name of the data variable that i wanna apply?

Answer 1

methods:{
    setBackground: function(val, element){
        if(val < 15){
            element.backgroundColor = "red";
        }
        else if(val < 50){
            element.backgroundColor = "orange";
        }
        else{
            element.backgroundColor = "green";
        }
    }
},
watch: {
    valueYou: function(val){
        this.setBackground(val, this.progressYou);
    },
    valueMonster: function(val){
        this.setBackground(val, this.progressMonster);
    }
}

Answer 2

Create a function that turns the value into the color:

function progressColor(p) {
  if (p < 15) return "red";
  if (p < 50) return "orange";
  return "green";
}

Now call that in your object:

watch: {
  valueYou: function (val) {
    this.progressYou.backgroundColor = progressColor(val);
  }
}