The JavaScript object freeze method is used to make an object immutable, i.e. you cannot change its properties. It accepts an object and returns the same object. Now the object cannot have any of its properties removed or any new properties added.
Object.freeze(obj);JavaScript Object freeze example
Simple example code.
<!DOCTYPE html>
<html>
<body>
<script>
const obj = {
prop: 100
};
Object.freeze(obj);
obj.prop = 200;
console.log(obj.prop);
console.log(obj)
</script>
</body>
</html>
Output:
Can’t mutate a frozen object
object1 = {
prop1: 1,
prop2: 2
}
object2 = Object.freeze(object1);
console.log(object1 === object2); // both objects are refer to the same instance
object2.prop3 = 3; // no new property can be added, won't work
delete object2.prop1; // no property can be deleted, won't work
console.log(object2); // object unchangedObjects with references aren’t fully frozen
const object = {
prop1: 1,
nestedObj: {
nestedProp1: 1,
nestedProp2: 2,
}
}
const frozen = Object.freeze(object);
frozen.prop1 = 5; // won't have any effect
frozen.nestedObj.nestedProp1 = 5; //will update because the nestedObject isn't frozen
console.log(frozen);Do comment if you have any doubts or suggestions on this JS object topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version