In Javascript, Object has an assign function. Since an object literal has a __proto__ of Object.prototype, why can't an object literal use assign and must go through Object directly?
Object.assign({}, {hello: 'world'})
const o = {};
o.assign({add: 'more stuff'})
The Object prototype does not have the method assign on it. Open the F12 console and type Object.prototype to see what is available on the base object prototype.
Object.assign is considered a static method, not an instance method.
It's because assign is sort of a static function. It is not defined into the prototype.
Here is an example:
function SomeClass(foo) {
this.foo = foo;
}
// this is a method, it is attached to the prototype
SomeClass.prototype.showFoo = function() {
console.log(this.foo);
}
// this is a static method, it is not attached to the prototype
SomeClass.bar = function() {
console.log("bar");
}
var instance = new SomeClass("foo");
console.log(instance.showFoo); // OK
console.log(instance.bar); // not OK
console.log(SomeClass.showFoo); // not OK
console.log(SomeClass.bar); // OK
static keyword. Javascript doesn't have static functions, it just mimics them.var k = 1 means that the data type of k isn't the actually int, it just mimics intvar k = 1 just mimics int because javascript is an untyped language. It only has one type for numeric values called number.The assign function isn't in the prototype property of Object and just the properties and methods defined on it can be accessed by created objects, to prove that let's do this:
Object.prototype.assign = function(){}; // this create a function called assign in the prototype property of Object
var obj = {};
obj.assign(); // Now we can access the assign function with the object literal
Hope this help.
o.add = 'more stuff';