JavaScript Object.seal()
Example
"use strict"
// Create Object
const person = {
firstName: "John",
lastName: "Doe",
age: 50,
eyeColor: "blue"
};
// Seal Object
Object.seal(person)
// This will throw an error
delete person.age;
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More Examples Below !
Description
The Object.seal() method prevents additions or deletions of new properties.
The Object.seal() method makes existing properties non-configurable.
The Object.seal() method will fail silently in non-strict mode.
The Object.seal() method will throw a TypeError in strict mode.
The Object.isSealed() method can be used to check if an object is sealed.
Related Methods:
Object.preventExtensions() allows modifications, but prevents addition of properties.
Object.seal() allows modifications, but prevents additions and deletions of properties.
Object.freeze() prevents modifications, additions and deletions of properties.
Object.isExtensible() returns true if an object is extensible.
Object.isSealed() returns true if an object is sealed.
Object.isFrozen() returns true if an object is frozen.
Syntax
Object.seal(object)
Parameters
| Parameter | Description |
| object | Required. The object to seal. |
Return Value
| Type | Description |
| Object | The sealed object. |
More Examples
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
Object.seal(fruits);
// This will throw an error:
fruits.push("Kiwi");
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Browser Support
Object.seal() is an ECMAScript5 (ES5) feature.
ES5 (JavaScript 2009) is fully supported in all modern browsers since July 2013:
| Chrome 23 |
IE/Edge 11 |
Firefox 21 |
Safari 6 |
Opera 15 |
| Sep 2012 | Sep 2012 | Apr 2013 | Jul 2012 | Jul 2013 |
