1.0.1 • Public • Published

    Keyword arguments for Javascript. Similar to python's kwargs

    This little tool gives you the ability to use keyword arguments support for your functions. So you can either specify each argument as you wish or use the arguments regularly. In fact you can do both at the same time.

    Another feature is to have the ability to set default values for your function arguments without changing or adding any code to your function.


    Just include the script on your site. That's it. When included it will add a new method called kwargs to Function prototype and you can use it like this:

    var functionName = function(arg1, arg2){
        // code


    Just write your function as you would normally, and don't worry about the arguments size. just call .kwargs() and rest will be handled.

    var test = function(arg1, arg2, arg3){
        // Your code

    Now, if you want you can pass all arguments in a single object and they all will be mapped to their correct places

        arg3: 'val3',
        arg1: 'val1',
        arg2: 'val2'

    You can also use your function like you would normally use

    test('val1', 'val2', 'val3');

    the best part is that you can do both

    test('val1', {
        arg3: 'val3',
        arg1: 'val1',

    Using Default values for arguments

    Let's say we have this function that says Hello to a given name.

    var greeting = function(name){
        return "Hello " + name;
    greeting('Frank'); // -> Hello Frank

    If no name is given, we want it to return "Hello World", usually you would have to add conditions to your function and check for existence of name argument. kwargs automatically handles that for you.

    var greeting = function(name){
        return "Hello " + name;
    }.kwargs({name: 'World'}); // Set a default value for your argument and 
                               // it will be used when this argument is empty
    // Here are the results
    greeting('Frank'); // -> Hello Frank
    greeting(); // -> Hello World

    A real example

    Let's say we have a function that receives a lot of arguments and generates a name with prefixes and suffixes when provided.

    var name = function(firstName, lastName, middleName, prefix, suffix){
        var name = [];
        return name.join(' ');

    Now, when we want create a name with only a suffix, all we have to do is to provide the name and suffix. You can only pass required arguments without changing anything on your function code.

    name('John', 'Doe', { suffix:'Ph.D.' });
    // -> John Doe Ph.D.
    name('Max', 'Fightmaster', { prefix: 'Staff Sgt.' })
    // -> Staff Sgt. Max Fightmaster
    name('Isaac', 'Newton', { prefix: 'Sir', suffix: 'PRS MP'});
    // -> Sir Isaac Newton PRS MP

    Important Note

    If last argument passed is an object, code assumes it's a kwargs object, if your function accepts objects as arguments you should be careful about this, here is an example.

    // in both cases, `anObject` argument will be interpreted as `kwargs` object and be ignored
    myFunc('val', anObject);

    to avoid this problem you have two solutions

    myFunc(anObject, {}); // passing last argument as an empty object
    // or using the options method and passing your object in kwargs
      arg1: anObject


    MIT License




    npm i kwargsjs

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    • serkanyersen