Attaching Event In Loop

what am doing is attaching event on a class using a loop and index values are being used in the event handler code. here is my code: var classElements=document.getElementsByClassNa

Solution 1:

JavaScript closes over the object and evaluates it later when it is called. At the time it is called, i is 4.

I think you want something like:

var classElements=document.getElementsByClassName("a");
for(var i=0; i<4; i++)
{
    classElements[i].onClick=function(j) { 
       returnfunction(){
          alert("Clicked button : "+j);
       };
    }(i);
}

EDIT: shown with named functions to make the code more clear

var classElements=document.getElementsByClassName("a");
for(var i=0; i<4; i++)
{
    var makeFn = function(j) { 
       returnfunction(){
          alert("Clicked button : "+j);
       };
    };
    classElements[i].onClick = makeFn(i);
}

Solution 2:

You need a closure in order to capture the changes of i. As Lou stated this is due to post evaluation.

var classElements=document.getElementsByClassName("a");
for(var i=0; i<4; i++)
    classElements[i].onclick = (function(i){
          returnfunction(){ alert("Clicked button : " + i) }; 
       })(i);