js_preventExtensions.js

var preventExtensionObject = {
    value1 : 1,
    value2 : 2
};
 
Object.preventExtensions(preventExtensionObject);
console.log(Object.isExtensible(preventExtensionObject)); // false
 
// 삭제 가능
delete preventExtensionObject.value1;
console.log(preventExtensionObject.value1); // undefined
 
// 변경 가능
preventExtensionObject.value2 = 3;
console.log(preventExtensionObject.value2); // 3
 
// 객체 추가 불가
preventExtensionObject.value3 = 3;
console.log(preventExtensionObject.value3); // undefined