JavaScript Function Invocation

call() allows a function belonging to one object to be executed./method assigns to another object and calls it.

function Product(name, price) {
　　this.name = name;
　　this.price = price;
}
function Food(name, price) {
　　Product.call(this, name, price);
　　this.category = "food";
}
document.write(new Food("cheese",　12).name);

In the example, call() is directed to the function/The method provides a new value this. By calling it, you can write a method once and then inherit the method in another object without rewriting the method for the new object.

Use call to link the object's constructor function using a call

You can use call() to link the object's constructor function, similar to Java.

function Product(name, price) {
　　this.name = name;
　　this.price = price;
}
function Food(name, price) {
　　Product.call(this, name, price);
　　this.category = "food";
}
function Toy(name, price) {
　　Product.call(this, name, price);
　　this.category = "toy";
}
let cheese = new Food("cheese",　12);
let robot = new Toy("robot",　85);

Calling a function using a call without specifying parameters

In the following example, we call the display function without passing any parameters:

var name = "Seagull";
function display() {
　　document.write(this.name);
}
display.call();