Accessing an Object’s Keys, Values, and Entries in JavaScript

Let’s dive into objects

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• Object.keys(obj) → returns an array of a given object’s property names.
• Object.values(obj) → returns an array of a given object's own property values.
• Object.entries(obj) → returns an array of a given object’s own string-keyed property [key, value] pairs.

var user = {
    name : "John",
    profession : "👨‍⚕️",
    salary  : 10000
}
Object.keys(user); // ["name", "profession", "salary"]
Object.values(user); // ["John", "👨‍⚕️", 10000]
Object.entries(user); 
//output
0: (2) ["name", "John"]
1: (2) [“profession”, “👨‍⚕️”]
2: (2) [“salary”, “10000]
length: 3

All the above three methods return only the enumerable property of the object.

var user = {
    name : "John"
}
Object.defineProperty( user , 'salary', {
   value: 10000,
   enumerable: false
});

In the above code, we define a property salary and set enumerable property as false.This will make the salary hidden from the Object.keys.

Object.keys(user); ["name"]
Object.values(user); ["John"]
Object.entries(user); //  ["name", "John"]

We cannot loop through the symbol properties of the object.

var user = {
    name : "John"
}

let Passcode = Symbol("Passcode");
user[Passcode] = "1234";

Now we have set the symbol as a property of the object, but this will not be accessible using the three methods above.

Object.keys(user); //["name"]
Object.values(user); // ["John"]
Object.entries(user); //  ["name", "John"]

To access the symbol property of the object, we can use getOwnPropertySymbols().

Object.getOwnPropertySymbols(user); //[Symbol(Passcode)]