Skip to main content

JavaScript: Flexible Arguments

In many use-cases it's very useful to know total number of in-parameter and there type of param.

function testArgs(){
 var args = arguments,
 param = args[0],
 type =;
 console.log('total number of in param: '+args.length);
 console.log('type of first param: '+type);
-> testArgs('test');
//total number of in param: 1
//type of first param: [object String]
-> testArgs(3, 3);
//total number of in param: 2
//type of first param: [object Number]

Above function will print the number of parameter pass to it and first parameter type.
Jquery use this trick to deal with optional parameter (like. jQuery.extend, jQuery.when etc.)

Few more example on this concept.
##Add function with flexible argument
function add(){
 var total = 0,
  arg = arguments;
 for(var i =0; i< arg.length; i++){
  total += arg[i];
 return total;
->add(1, 2, 5, 22); //ans: 30
->add(1, 2); //ans: 3

##find n highest number from the array
function highest(){ 
 function makeArray(array){ 
  //Arrays have .slice and .splice methods which return new arrays.
  return Array() array );
 return makeArray(arguments).slice(1).sort(function(a,b){ 
  return b - a; 
->highest(1, 1, 2, 3)[0]; //1st highest ans: 3
->highest(3, 1, 2, 3, 4, 5)[1]; //2nd highest ans: 4

John Resig wrote a function for method overloading and he is using "arguments.length" to identify which function have to call
link of original post
// addMethod - By John Resig (MIT Licensed)
function addMethod(object, name, fn){
    var old = object[ name ];
    object[ name ] = function(){
        if ( fn.length == arguments.length )
            return fn.apply( this, arguments );
        else if ( typeof old == 'function' )
            return old.apply( this, arguments );

//how to use it with function
function Users(){
  addMethod(this, "find", function(){
    // Find all users...
  addMethod(this, "find", function(name){
    // Find a user by name
  addMethod(this, "find", function(first, last){
    // Find a user by first and last name

//how to use with object prototype
function Users(){}
addMethod(Users.prototype, "find", function(){
  // Find all users...
addMethod(Users.prototype, "find", function(name){
  // Find a user by name
addMethod(Users.prototype, "find", function(first, last){
  // Find a user by first and last name


Popular posts from this blog

ERROR: Ignored call to 'alert()'. The document is sandboxed, and the 'allow-modals' keyword is not set.

Recently I found this issue while writing code snippet in "JSFiddle". And after searching, found this was happening because of new feature added in "Chrome 46+". But at the same time Chrome doesn't have support for "allow-modals" property in "sandbox" attribute. Chromium issue for above behavior: To make it work you have to add "allow-scripts allow-modals" in "sandbox" attribute, and use "window.alert" instead of "alert". <!-- Sandbox frame will execute javascript and show modal dialogs --> <iframe sandbox="allow-scripts allow-modals" src="iframe.html"> </iframe> Feature added: Block modal dialog inside a sandboxed iframe. Link: Feature working Demo page:

Application Design Notes

Don’t be afraid to write your own code, but be absolutely sure you need to Don't reinvent the wheel Learn more about your libraries and take full advantage  Date time calculation is hard ( leap second ,  leap year ), use trusted library  js-joda ,  momentJs ,  joda (java) Simple is better than perfect (nearly) every time If you can deliver a sub-optimal solution (that solves the problem but has known limitation) in a week instead of a full featured one in a month DO, IT Simple system are Easy to reason about  Easy to debug Easy to refactor Easy to learn Simple doesn't mean you skip good engineering, but you can use duct tape. Build things the right way from the start, refactoring is hard and expensive Security Manage and store passwords securely Telemetry Common retrofitting "grunt work" Internationalization + localization Web Content Accessibility Factoring and styling HTML UI Adding unit test to an existing codebase LOG LOG LOG Log, but do it right We spend lot of t

How to store user password at server!!!

Trick is, you should never store user password… never ever. Now the real question is, then how to authenticate and authorize the user with password. And answer is when user enter the password, we should encrypt the password and store the hints. So next time when user enter the password we follow the same process and compare hints, if both hints are same then password is matched, else it is wrong password. Next question will be, what kind of hints, and how to generate these hints. In simple term hints are the obfuscated and fragmented form of user password. And very important part is hints generation process, which have to be collision resistant , means there will be very less possibility to find the data which generate same hints (like Cryptographic hashing functions ). Below is the simple checklist of password hashing and storing, which you should always keep in mind. PS You're Probably Storing Passwords Incorrectly Storing Passwords - done rig