There are no overloads in JS in the form in which they exist in Java or C#. But I’ll show you an examples of using the similarity of overloads
- Rest Parameters in functions
- Rest Parameters in constructors
- Overloading in constructors, TS
- Overloading in functions, TS
- Arguments object (Don’t use it)
Rest Parameters in functions
const sum = (...args) => {
let counter = 0;
for (let i = 0; i < args.length; i++) {
counter += args[i];
}
return counter;
};
sum(1, 2) // 3
sum(2, 3, 5); // 10...args - is an additional parameters
const example = (a, b, ...args) => {
// args[0] - is third parameter
// args[1] - is fourth parameter
// etc
return a + args[0];
};
example(1, 4, 5) // 6
example(1, 4) // NaNRest Parameters in constructors
class Point {
constructor(...args) {
this.x = args[0] ?? 0;
this.y = args[1] ?? 0;
}
printСoordinates() {
console.log(this.x, this.y);
}
}
const p = new Point(1, 2);
const p1 = new Point(1, 2, 3); // third parameter will be ignored
p.printСoordinates(); // 1 2
p1.printСoordinates(); // 1 2Overloading in constructors, TS
TS gives us a new syntax for overloads
class Point {
#x: number;
#y: number;
constructor();
constructor(x: number);
constructor(x: number, y: number);
constructor(...args: number[]) {
this.#x = args[0] ?? 0;
this.#y = args[1] ?? 0;
}
printСoordinates = () => {
console.log(this.#x, this.#y);
}
}
const p = new Point(1);
const p1 = new Point(1, 2, 3); // Expected 0-2 arguments, but got 3
p.printСoordinates(); // 1 0and suitable tips
Overloading in functions, TS
class MyClass {
method(): void;
method(a: number): void;
method(a: number, b: number): void;
method(a: number, b: number, c: number): void;
method(...args: number[]): void {
// logic
}
}Arguments object
Use rest parameters instead of arguments object!!!
arguments - an object that is similar to an array. It has indexes arguments[0]
and .length. Also arguments doesn’t work with arrow functions
function sum() {
let acc = 0;
for (let i = 0; i < arguments.length; i++) {
acc += arguments[i];
}
return acc;
}
sum(2, 3, 5); // 10
function example(a, b) {
// arguments[0] = a
// arguments[1] = b
return arguments[2];
}
example(1, 2, 3); // 3