1. Definition
In this tutorial we will take a look Object prototype and which methods does it provide. Let us get into it.
2. Objest.is()
Object.is() - JavaScript | MDN
In our first example we have and comprassion method which determines whether two values are the same value.
- Returns: a boolean indicating whether or not the two arguments are the same value.
Object.is(25, 25);
Object.is('foo', 'foo');
Object.is('foo', 'bar');
Object.is(null, null);
Object.is(undefined, undefined);
Object.is(window, window);
Object.is([], []);
var foo = { a: 1 };
var bar = { a: 1 };
Object.is(foo, foo);
Object.is(foo, bar);
Object.is(0, -0);
Object.is(+0, -0);
Object.is(-0, -0);
Object.is(0n, -0n);
Object.is(NaN, 0/0);
Object.is(NaN, Number.NaN)
3. Object.assign()
Object.assign() - JavaScript | MDN
The Object.assign() method copies all enumerable own properties from one or more source objects to a target object. It returns the modified target object
- Returns: The target object.
const target = { a: 1, b: 2 };
const source = { b: 4, c: 5 };
const returnedTarget = Object.assign(target, source);
console.log(target);
console.log(returnedTarget);
Properties in the target object are overwritten by properties in the sources if they have the same key. Later sources' properties overwrite earlier ones.
4. Object.entries()
Object.entries() - JavaScript | MDN
The Object.entries() method returns an array of a given object's own enumerable string-keyed property [key, value] pairs.
- Returns: An array of the given object's own enumerable string-keyed property [key, value] pairs.
- The ordering of the properties is the same as that given by looping over the property values of the object manually.
const object1 = {name: "David", age: 23};
for (const [key, value] of Object.entries(object1)) {
console.log(`${key}: ${value}`);
}
5. Object.prototype.hasOwnProperty()
Object.prototype.hasOwnProperty() - JavaScript | MDN
The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as its own property
- Returns: true if the object has the specified property as own property; false otherwise.
const object1 = {};
object1.property1 = 42;
console.log(object1.hasOwnProperty('property1'));
console.log(object1.hasOwnProperty('toString'));
console.log(object1.hasOwnProperty('hasOwnProperty'));
6. Object.keys()
Object.keys() - JavaScript | MDN
The Object.keys() method returns an array of a given object's own enumerable property names, iterated in the same order that a normal loop would.
const object1 = {
a: 'somestring',
b: 42,
c: false
};
console.log(Object.keys(object1));
7. Object.values()
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/values
The Object.values() method returns an array of a given object's own enumerable property values, in the same order as that provided by a for...in loop.
- Returns: An array containing the given object's own enumerable property values.
const object1 = {
a: 'somestring',
b: 42,
c: false
};
console.log(Object.values(object1));
8. Object.prototype.toString()
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toString
The toString() method returns a string representing the object.
- Returns: A string representing the object.
function Dog(name) {
this.name = name;
}
const dog1 = new Dog('Gabby');
Dog.prototype.toString = function dogToString() {
return `${this.name}`;
};
console.log(dog1.toString());
const o = new Object();
o.toString();
9. Optional Parameter for toString
For Numbers and BigInts toString() takes an optional parameter radix the value of radix must be minimum 2 and maximum 36.
By using radix you can also convert base 10 numbers (like 1,2,3,4,5,.........) to another base numbers, in example below we are converting base 10 number to a base 2 (binary) number.
let baseTenInt = 10;
console.log(baseTenInt.toString(2));
let bigNum = BigInt(20);
console.log(bigNum.toString(2));
10. Links
