python positional named arguments emulation using javascript

js_funny_args.js

"use strict";

function get_args(arguments_) {
    /* http://stackoverflow.com/questions/1007981/how-to-get-function-parameter-names-values-dynamically-from-javascript */
    var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
    var ARGUMENT_NAMES = /([^\s,]+)/g;
    var src = arguments_.callee.toString().replace(STRIP_COMMENTS, '');
    var pars = src.slice(src.indexOf('(')+1, src.indexOf(')')).match(ARGUMENT_NAMES);
    if (! pars) { pars = []; }
    var i, j;  

    // enable "arg1", "arg2", {"arg5":"xxx"}
    // where arg1, arg2 are positional arguments, arg5 is named arguments
    var out = {};
    for (i = 0; i < pars.length; ++i) {
        var argi = arguments_[i],
            is_named_args = false;
        if (typeof argi === "object"){
            is_named_args = true;
            var argi_keys = Object.keys(argi),
                pars_copy = JSON.parse(JSON.stringify(pars)),
                wanted_keys = pars_copy.splice(i);
            for (j = 0; j < argi_keys.length; ++j){
                if (wanted_keys.indexOf(argi_keys[j]) === -1) { 
                    is_named_args = false;
                    break;
                }  
            }                          
        }                              
        if (is_named_args) {           
            var named_args = argi;
            for (j = i; j < pars.length; ++j) {
                out[pars[j]] = named_args[pars[j]];
            }                          
            break;                     
        }                              
        else {                         
            // position argument       
            out[pars[i]] = arguments_[i];
        }                      
    }                          
    return out;                
}                                  

function test_me(arg1, arg2, arg3, arg4, arg5) {
    var args = get_args(arguments);
    console.log(args);             
}                                  

// emulate python's named argument call : test_me("who", "are", arg5="you")
test_me("who","are",{arg5:"you"});     
// prints {arg1:"who", arg2:"are", arg3:undefined, arg4:undefined, arg5:"you"}

test_me("who","are",{fag:"you"});     
// prints {arg1:"who", arg2:"are", arg3:{fag:"you"}, arg4:undefined, arg5:undefined}