FUNCTION OVERLOADER

This library/helper is solution for lack of function overloading in javascript. You can define different behaviours depending on provided arguments to the function.

install

npm install function-overloader

usage

First import/require this library

import Overload from "function-overloader";

then for function or method define rules and callbacks

const rulesForSomeFunction = 
    Overload
       .when(<list of rules>)
       .do(<callback called when above rules pass>)
       .when(<list of other rules>)
       .do(<callback called when above rules pass>)
       // you can add as many rules as you need

Next we call rulesForSomeFunction.execute(...arguments) inside overloaded function or method

function someOverloadedFunction() {
    return rulesForSomeFunction
        .execute(...arguments);
}

Right when you call someOverloadedFunction with different arguments it will call correct callback

example

First example

Lets assume that we need function which can

• accept object with properties name and age where name is string and age a number.
• accept two arguments where former is a string and second a number.
• accept two arguments where former is a number and second a string.

All variants should return string with format name_age

 
import Overload from "function-overloader";
 
function joinNameAndAge() {
    return Overload
       .when(Overload.Interface({
           name: Overload.STRING,
           age: Overload.NUMBER
       }))
       .do(objWithNameAndAge => objWithNameAndAge.name + objWithNameAndAge.age)
       .when(Overload.String, Overload.NUMBER)
       .do((name, age) => name + age)
       .when(Overlod.Number, Overload.String)
       .do((age, name) => name + age)
       .execute(...arguments);
}
 
joinNameAndAge({
    name: "Test",
    age: 1
}); // Test1
joinNameAndAge("Test", 2); // Test2
joinNameAndAge(3, "Test"); // Test3

API

.when()

.when()

It is for describe when to run related do method. Return object with do method

Accept multiple values that will descibe function.

There is lot of possible values, Some with additional params. All of them are available here https://github.com/uhlryk/check-complex-types

All of them are available in Overload object. e.g. Overload.ANY()

.do()

Is accessible only from object returned from .when method

.do()

Accept callback function which should be called if previous .when match arguments.

.else()

.else()

Accept callback function. Will invoke it when other criteria are not met.

.elseThrow()

.elseThrow()

Throws TypeError if not any above condition met

.execute()

.execute()

accept function arguments. It is possible by passing them one by one, but preferred why is to just pass spread ...arguments.

License

MIT