setInterval inside a class

[Jim Red]

hello, how can i set an interval inside a class

exmpl.

var Class = (function() {
var interval = undefined;

function initInterval(instance) {
interval = setInterval("doSomething", 1000, instance);
}

function doSomething(instance) {
alert(instance.message);
}

function Constructor() {
this.message = "hello world";
}

Constructor.prototype.init = function() {
initInterval(this);
}

return Constructor;
})();


is not working correct. doSomething is not known. i think, setInterval
is not inside the class, so doSomething is private and unknown for the
interval

can anyone help?

//jim

 

[Yann-Erwan Perio]

Jim Red wrote:

Hi,

var Class = (function() {
var interval = undefined;

function initInterval(instance) {
interval = setInterval("doSomething", 1000, instance);
}

function doSomething(instance) {
alert(instance.message);
}

function Constructor() {
this.message = "hello world";
}

Constructor.prototype.init = function() {
initInterval(this);
}

return Constructor;
})();

When using a string for the first argument of setInterval, the string is
evaluated in the global context; however "doSomething" is not global, it
is a local member of Class. You should therefore use a function rather
than a string for you first argument, since nested function still have
access to outer variables (closures), and you can then have a better
control of scopes. See below.


---
var MyClass = (function() {
var interval;

function initInterval(instance) {
interval = setInterval(
function() {
instance.doSomething();
},
2000
);
}

function Constructor() {
this.message = "hello world";
}

Constructor.prototype.init = function() {
initInterval(this);
}

Constructor.prototype.doSomething = function() {
alert(this.message);
}

return Constructor;
})();

var foo=new MyClass();
foo.init();

 

[Thomas 'PointedEars' Lahn]

hello, how can i set an interval inside a class
[...]

Note that the version of J(ava)Script you are referring to does not support
classes, it supports (only) prototype-based inheritance. Your source code
presents a so far unnecessary encapsulation of the methods of a prototype
within a so-called "constructor function" -- it is a factory which is not
needed here nor does help anything to keep the global scope sober.


PointedEars