revision:
The Object.isSealed() static method determines if an object is sealed.
Object.isSealed(obj)
Parameters:
obj : required. The object which should be checked.
: optional. .
const object1 = {
property1: 42
};
console.log(Object.isSealed(object1));
// Expected output: false
Object.seal(object1);
console.log(Object.isSealed(object1));
// Expected output: true
<div>
<p id="seal-1"></p>
<p id="seal-2"></p>
<p id="seal-3"></p>
<p id="seal-4"></p>
<p id="seal-5"></p>
<p id="seal-6"></p>
<p id="seal-7"></p>
<p id="seal-8"></p>
<p id="seal-9"></p>
</div>
<script>
// Objects aren't sealed by default.
const empty = {};
Object.isSealed(empty); // false
document.getElementById("seal-1").innerHTML = "is sealed ? : " + Object.isSealed(empty);
// If you make an empty object non-extensible, it is vacuously sealed.
Object.preventExtensions(empty);
Object.isSealed(empty); // true
document.getElementById("seal-2").innerHTML = "is sealed ? : " + Object.isSealed(empty);
// The same is not true of a non-empty object, unless its properties are all non-configurable.
const hasProp = { fee: "fie foe fum" };
Object.preventExtensions(hasProp);
Object.isSealed(hasProp); // false
document.getElementById("seal-3").innerHTML = "is sealed ? : " + Object.isSealed(hasProp);
// But make them all non-configurable and the object becomes sealed.
Object.defineProperty(hasProp, "fee", {
configurable: false,
});
Object.isSealed(hasProp); // true
document.getElementById("seal-4").innerHTML = "is sealed ? : " + Object.isSealed(hasProp);
// The easiest way to seal an object, of course, is Object.seal.
const sealed = {};
Object.seal(sealed);
Object.isSealed(sealed); // true
document.getElementById("seal-5").innerHTML = "is sealed ? : " + Object.isSealed(sealed);
// A sealed object is, by definition, non-extensible.
Object.isExtensible(sealed); // false
document.getElementById("seal-6").innerHTML = "is sealed object extensible? : " + Object.isExtensible(sealed);
// A sealed object might be frozen, but it doesn't have to be.
Object.isFrozen(sealed); // true
// (all properties also non-writable)
document.getElementById("seal-7").innerHTML = "is sealed object frozen? : " + Object.isFrozen(sealed);
const s2 = Object.seal({ p: 3 });
Object.isFrozen(s2); // false
// ('p' is still writable)
document.getElementById("seal-8").innerHTML = "is sealed object frozen? : " + Object.isFrozen(s2);
const s3 = Object.seal({
get p() {
return 0;
},
});
Object.isFrozen(s3); // true
// (only configurability matters for accessor properties)
document.getElementById("seal-9").innerHTML = "is sealed object frozen? : " + Object.isFrozen(s3);
</script>
<div>
<p id="seal-10"></p>
<p id="seal-11"></p>
<p id="seal-12"></p>
</div>
<script>
// creating an object constructor and assigning values to it
const object = {
property: 'hi ninjasforninjas'
};
// checking whether the object is sealed or not
console.log(Object.isSealed(object));
document.getElementById("seal-10").innerHTML = "is object sealed? : " + Object.isSealed(object);
// Using seal() method to seal the object
Object.seal(object);
// checking whether the object is frozen or not
console.log(Object.isSealed(object));
document.getElementById("seal-11").innerHTML = "is object sealed? : " + Object.isSealed(object);
</script>