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JavaScript In Practice: ES6 And Beyond

Property Access and Modification

Understand how to use the Reflect API to access, modify, define, and delete properties of JavaScript objects. Learn methods like Reflect.get, Reflect.set, and Reflect.defineProperty, and discover how to manage object extensibility in practical scenarios.

We'll cover the following...

Reflect.has determines if a property exists for a given target object. The call enumerates all properties, not only own properties.

Node.js
let target = class Account {
    constructor( name, email ) {
        this.name = name;
        this.email = email;
    }  
    get contact() {
        return `${this.name} <${this.email}>`;
    }
};
let args = [ 
    'Zsolt', 
    'info@zsoltnagy.eu' 
];
let myAccount = Reflect.construct(
    target,
    args );
console.log(Reflect.has( myAccount, 'name' ));
console.log(Reflect.has( myAccount, 'contact' ));

Reflect.ownKeys returns all own properties of a target in an array.

Node.js
console.log(Reflect.ownKeys( myAccount ));

Reflect.get gets a property based on a key. As an optional parameter, the this context can be specified.

Node.js
console.log(Reflect.get( myAccount, 'name' ));
//> "Zsolt"
console.log(Reflect.get( myAccount, 'contact' ));
//> "Zsolt - 555-1269"

Getting the name property of myAccount is straightforward. In the second example, getting the contact property requires the execution ...