JavaScript In Practice: ES6 And Beyond/

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Property Access and Modification

Property Access and Modification

access, modify (update and delete) properties of Objects

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

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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.

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

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

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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, ...