how to write something like setTimeout

[Antony Sequeira]

Hi
While looking at some code I realized that the built in
setTimeout
function takes a string that is later
evaluated in the original caller's context.
How does one achieve something similar in user defined functions.

-Antony

 

[Lee]

Antony Sequeira said:

Hi
While looking at some code I realized that the built in
setTimeout
function takes a string that is later
evaluated in the original caller's context.
How does one achieve something similar in user defined functions.

You use setTimeout.
In other words, your question isn't clear.
Why won't setTimeout do what you want?

 

[Yann-Erwan Perio]

While looking at some code I realized that the built in
setTimeout
function takes a string that is later
evaluated in the original caller's context.

This original context is always the global object (window). However, you
can perfectly use a function reference or a function expression instead
of a string as the first argument for setTimeout - this isn't supported
by old browsers though, which would then call the toString() method for
the function while evaluating the setTimeout first argument - test
accordingly.

function foo(){
var bar="hello, world!";
setTimeout(
function(){
alert(bar);
},
1000
);
}

Using a function expression is much more powerful than using a string
argument, since you can control the scope chain and add a specific scope
object, just for this function (either using an outer function or a
"with" statement).

---
setTimeout(
(function(){
var foo=0, bar=0;
return function(){
window.status="foo:"+foo+", bar:"+bar;
if(foo++<1000 && bar-->-1000)
setTimeout(arguments.callee, 50);
}
})(),
50
);
---


---
with({foo:0,bar:0}){
setTimeout(
function(){
window.status="foo:"+foo+", bar:"+bar;
if(foo++<1000 && bar-->-1000)
setTimeout(arguments.callee, 50);
},
50
);
}

 

[Antony Sequeira]

This original context is always the global object (window).

Ok. Thanks for correcting my mis-conception and for the example code.
-Antony