In JavaScript, every object has a prototype, including the prototype object. This “chain” goes all the way back until it reaches an object that has no prototype, usually Object‘s a prototype. Because each object has a private property that holds a link to another object that’s why it is called a prototype chain in JavaScript.
function Dog(name) {
this.name = name;
}
Object.prototype.isPrototypeOf(Dog.prototype);The prototype is basically a property of a JavaScript function. The prototype’s version of “Inheritance” involves adding another link to the end of this prototype chain, as shown above.
JavaScript prototype chain
Simple example code.
<!DOCTYPE html>
<html>
<body>
<script>
const myObject = {
city: 'Madrid',
greet() {
console.log(`Greetings from ${this.city}`);
}
}
myObject.greet();
console.log(myObject.toString())
</script>
</body>
</html> Output:
Read more: https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Objects/Object_prototypes
- When you access a property or method on an object, JavaScript first checks if the object itself has that property or method. If it doesn’t find it, it looks up the prototype chain.
- JavaScript will continue to follow the
__proto__chain until it finds the property or method or reaches the end of the chain.
Do comment if you have any doubts or suggestions on this JS prototype topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version