JavaScript: Passing parameters to a callback function

Question

I'm trying to pass some parameter to a function used as callback, how can I do that?

This is my try:

function tryMe(param1, param2) {   alert(param1 + " and " + param2); }  function callbackTester(callback, param1, param2) {   callback(param1, param2); }  callbackTester(tryMe, "hello", "goodbye");

Answer 1

If you want something slightly more general, you can use the arguments variable like so:

function tryMe(param1, param2) {   alert(param1 + " and " + param2); }  function callbackTester(callback) {   callback(arguments[1], arguments[2]); }  callbackTester(tryMe, "hello", "goodbye");

But otherwise, your example works fine (arguments[0] can be used in place of callback in the tester)

Answer 2

This would also work:

// callback function function tryMe(param1, param2) {   alert(param1 + " and " + param2); }  // callback executer  function callbackTester(callback) {   callback(); }  // test function callbackTester(function() {   tryMe("hello", "goodbye"); });

Another Scenario :

// callback function function tryMe(param1, param2, param3) {   alert(param1 + " and " + param2 + " " + param3); }  // callback executer  function callbackTester(callback) {   //this is the more obivous scenario as we use callback function   //only when we have some missing value   //get this data from ajax or compute   var extraParam = "this data was missing";    //call the callback when we have the data   callback(extraParam); }  // test function callbackTester(function(k) {   tryMe("hello", "goodbye", k); });