Protecting Your Objects: The Power of Sealing
When working with objects in JavaScript, it’s essential to understand how to control their behavior and prevent unwanted changes. One powerful tool in your arsenal is the Object.seal() method, which locks down an object to ensure its integrity.
What Does Sealing Do?
The Object.seal() method prevents new properties from being added to an object and marks all existing properties as non-configurable. This means you can no longer add, remove, or modify the properties of the object. However, you can still change the values of existing writable properties.
Sealing in Action
Let’s take a look at an example:
“`javascript
let obj = { foo: ‘bar’, value: 10 };
Object.seal(obj);
// We can modify existing writable properties
obj.value = 20;
// But we can’t add new properties
obj.newProperty = ‘newValue’; // silently fails in non-strict mode
// And we can’t redefine existing properties
Object.defineProperty(obj, ‘foo’, { value: ‘newBar’ }); // throws TypeError
“`
Key Takeaways
- Sealing an object makes its properties fixed and immutable.
- The values of present properties can still be changed if they are writable.
- Use
Object.isSealed()to check if an object is sealed or not. - Attempting to convert a data property to an accessor or vice versa will fail silently or throw a TypeError.
By mastering the Object.seal() method, you can ensure the integrity of your objects and prevent unwanted changes. Take control of your code and start sealing your objects today!