Function "remembers" value problem

Question

This is a simplified partial version of my code to demonstrate the issue:

function testFunc(){
    var randomNum = Math.floor( Math.random() * 100 );

  if( !flag ){
      addEvents();
     flag = true;
  };

    function checkNumber(){
       alert(randomNum)
    }

  function addEvents(){
     $("#someElement").click(function(e){ checkNumber() });
  }
}

I want to bind the click event only ONCE for this element, but use outside variable that changes from someplace else. thing is, this always alerts randomNum with the initial value it had when the bind first took place!

why doesn't it "reads" the variable everytime click is triggered?

Answer 1

You are setting a value to a global variable. Then you are alert'ing the value on the button click. Value was set only once and will not change on every click of the button.

Answer 2

is it really a global? try alerting window.randomNum

Answer 3

This might have something to do with functions insude functions. When you do:

function checkNumber() {
    alert(randomNumber);
}

I think is the same as doing:

myFunc = function checkNumber() {
    alert(randomNumber);
}

And is therefore set, as if randomNumber was final. If you need to use randomNumber you should either move it outide that scope and make it global, or better, pass it through the functions as a parameter:

function checkNumber(myNumber) {
    alert(myNumber);
}

Answer 4

Why don't you stick the randomNumber up a custom attribute of the element you're adding the clickevent to?

function testFunc(){
    var randomNum = Math.floor( Math.random() * 100 );
    $("#someElement").attr("randomNum", randomNum);

    if( !flag ){
        addEvents();
        flag = true;
    };

    function checkNumber(){
        alert($("#someElement").attr("randomNum"))
    }

    function addEvents(){
        $("#someElement").click(function(e){ checkNumber() });
    }
}

That way it always stays with the element, but is callable from allover the place. Pretty messy, but it should work.