[Template] Javascript Functions

Been dealing with Javascript functions lately, I find that these are the most-frequently-used input parameters for all a typical function:
  1. data
  2. url (optional) 
  3. callback (optional)

A good JS function should readily accept these parameters. And a typical Javascript function call would be like:
somefunction( {data: value, data2: value2 }, [url], [callback()] );
We know that in PHP we can use the following method to write a "optional" second (or third) input parameter.
function somefunction( $data, $callback = FALSE); 
This way, if the second argument is not supplied, $callback will be automatically assigned to FALSE. Its a good practice to set a default value for a variable.

After Googling around, I found that Javascript is event better at handling such case. We can take in as many optional input parameters, in no specific order. But the trade-off is, we need a check for the input parameter type.

Stackoverflow has this excellent post on the template for checking input argument type.

function getData ([id, parameters, callback]) {
  var id = arguments[0], parameters, callback;

  if (arguments.length == 2) { // only two arguments supplied
    if (Object.prototype.toString.call(arguments[1]) == "[object Function]") {
      callback = arguments[1]; // if is a function, set as 'callback'
    } else {
      parameters = arguments[1]; // if not a function, set as 'parameters'
  } else if (arguments.length == 3) { // three arguments supplied
    parameters = arguments[1];
    callback = arguments[2];
  // do something here...
  // ...
  // and finally, on complete run the callback function

This is... the function template which is usually used in jQuery too!


Actually callback function can be easily done in jQuery. Not the correct way though.
  // The functions to execute after the first function finish executing.

If you are new to Javascript frameworks, heres a good comparison of the performance of the popular frameworks. http://blog.creonfx.com/javascript/mootools-vs-jquery-vs-prototype-vs-yui-vs-dojo-comparison-revised



  1. Great Info. Thanks for the your effort. Appreciate it.

  2. Great Info. Thanks for the your effort. Appreciate it.



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