How to sort array of objects by value in JavaScript?

wioawyg.js

let arr = [
  { prop: "7" },
  { prop: "3" },
  { prop: "6" },
  { prop: "1" }
]

//Sort in ascending 
arr.sort(function(a, b) {
    return (a.prop - b.prop);
});


//Sort in descending 
arr.sort(function(a, b) {
    return (b.prop - a.prop);
});