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: /

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/niczak/4uNen/1/

• javascript
• jquery

• 2 declare var current = {}; outside the function – Pedro Estrada Commented Nov 25, 2013 at 22:17
• here is a jsfiddle jsfiddle/4uNen/2 – Pedro Estrada Commented Nov 25, 2013 at 22:33

3 Answers 3

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);

Your current is fine in that scope, it is your coords function that is not in the right scope. Put that in the global scope together with the freq variable:

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)
    };
}

function genSine(val1, val2) {

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

genSine(10, 20);

in typescript i did following code. in the below code i assign _this with the value of this

export class HomeComponent implements OnInit {
  lat: number = 22.008515;
  setMarker(){
   console.log('Inside setMarker Lat : '+this.lat); // 22.008515
    var _this = this;
    setInterval(function() {
     console.log('Inside setInterval this.lat : '+this.lat); // undefined
     console.log('Inside setInterval _this.lat : '+_this.lat); // 22.008515
    }, 8000)
  }
}