[JavaScript]オブジェクトを一定のままにします.freeze()

Object.freeze

How to Use

const obj = {
  prop: 42
};

Object.freeze(obj);

obj.prop = 33;
// Throws an error in strict mode

console.log(obj.prop);
// expected output: 42

Other examples

var o1 = {
    name: 'kim',
    score: [1, 2]
}
o1.name = 'lee';
console.log(o1);

var o1 = {
    name: 'kim',
    score: [1, 2]
}
Object.freeze(o1);
o1.name = 'lee';
console.log(o1);

Notice!

o1.city = 'seoul';

o1.score.push(3);

Object.freeze(o1.score);

C:\Users\yuri\Desktop\TEST\freeze-study\freeze-study.js:9
o1.score.push(3);
         ^

TypeError: Cannot add property 2, object is not extensible
    at Array.push (<anonymous>)
    at Object.<anonymous> (C:\Users\yuri\Desktop\TEST\freeze-study\freeze-study.js:9:10)

object.freezeとconstの違い

const o1 = {
    name: 'kim'
}
Object.freeze(o1);
const o2 = {
    name: 'lee'
}
o1 = o2;

PS C:\Users\yuri\Desktop\TEST\freeze-study> node .\freez_const.js
C:\Users\yuri\Desktop\TEST\freeze-study\freez_const.js:8
o1 = o2;
   ^

TypeError: Assignment to constant variable.
    at Object.<anonymous> (C:\Users\yuri\Desktop\TEST\freeze-study\freez_const.js:8:4) 
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47