Access global variables in setInterval()

Question

I have a function to generate some random-ish numbers and inside that function I make a call to setInterval() because I need those numbers to refresh every 2 seconds.

function genSine(val1, val2) {

    var freq = 0.1; // angular frequency

    var coords = function(x, y) {
        var amplitude = Math.floor((Math.random()*10)+1);
        var phase = Math.floor((Math.random()*20)+1);
        return {
            x : Math.sin(freq * (val1 + phase) * amplitude) + Math.floor((Math.random()*100)+1),
            y : Math.sin(freq * (val2 + phase) * amplitude) + Math.floor((Math.random()*100)+1)
        };
    }

    setInterval(function() {
        current = coords(50, 50);
        console.log('Val 1: ' + current.x);
        console.log('Val 2: ' + current.y);
    }, 2000);
}

genSine(10, 20);

This is all well and good, the values update as expected but my goal is to have two global variables (let's call them val1/val2) update within that setInterval() function. It appears I have a scoping issue because those variables are not accessible within the function and I can not access the 'current' variable from outside that function. I know I am missing something here, what is it?

Fiddle: http://jsfiddle.net/niczak/4uNen/1/

Answer 1

You just need to define var current = {}; in the global scope, and be sure not to define var current in any other scope. current=[whatever]; is fine, as long as there's no var.

Edit: I'm not sure what you did, but I fixed your fiddle with this code:

var current;
function genSine(val1, val2) {

    var freq = 0.1; // angular frequency

   var coords = function(x, y) {
        var amplitude = Math.floor((Math.random()*10)+10);
        var phase = Math.floor((Math.random()*20)+10);
        return {
            x : Math.sin(freq * (val1 + phase) * amplitude) + Math.floor((Math.random()*100)+1),
            y : Math.sin(freq * (val2 + phase) * amplitude) + Math.floor((Math.random()*100)+1)
        };
    }

    setInterval(function() {
        current = coords(50, 50);
        console.log(current);
        $(".display").html(JSON.stringify(current));
    }, 500);
}

genSine(10, 20);

setInterval(function() {
    $(".display2").html("d2:"+JSON.stringify(current));
}, 200);