참고
https://www.javascripttutorial.net/javascript-primitive-vs-reference-values
var foo = {
val: 10
}
var bar = foo;
console.log(foo.val, bar.val); // 10 10
console.log(foo === bar); // true
bar.val = 20;
console.log(foo.val, bar.val); // 20 20
console.log(foo === bar); // true
console.log(foo === { val: 10 }); // false
console.log(bar === { val: 20 }); // false
---------------------------------------
let player = { score: 3 };
function doStuff(obj) {
obj.score = 2;
}
doStuff(player);
console.log(player.score) // 2
-------------------------------
let score = 80;
function doStuff(value) {
value = 90;
}
doStuff(score)
console.log(score) // 80