Passing parameters to timers

tMesi · January 30th, 2009, 09:19 PM

Hi,

I just wanted to compliment Nicholas C. Zakas to his excellent book on JavaScript

. I have just bought the 2nd Edition and I enjoy reading it. But still after reading and experimenting - especially the advanced technique chapter (18) - here is a question about timers. I haven't found yet a good working solution how to pass parameters to a timer.

Example source:

{...}
setTimeout(function(parmeter1, parameter2,...) {...}, 10);
{...}

Do you have maybe a practical solution to this issue? Have ever come across such problem?

Yours
tMesi

nzakas · January 31st, 2009, 04:59 PM

Hi,

I think what you're looking for is not the ability to pass parameters, but rather the ability to bind parameters to a function that you've passed into setTimeout(). To do that, you can use either the curry() function described in the same chapter or the last version of the bind() function:

Code:

var param1 = 2;
var param2 = 4;

function functionToPass(arg1, arg2){

}

setTimeout(bind(functionToPass, this, param1, param2), 10);

This ensures that param1 and param2 are bound to functionToPass() when the timer is executed. Hope this helps.

-Nicholas

speednet · March 21st, 2009, 07:09 PM

Quote:

Originally Posted by nzakas

Code:

var param1 = 2;
var param2 = 4;

function functionToPass(arg1, arg2){

}

setTimeout(bind(functionToPass, this, param1, param2), 10);

This ensures that param1 and param2 are bound to functionToPass() when the timer is executed.

Just wanted to note that you must be referring to the bind() function found on page 597, rather than the more simple version found on page 595. This revelation comes after spending several minutes trying to figure out how the one on page 595 could possibly work for this issue.

(It may be useful to add page 597 to the index ("595, 597") to alert readers to the second version of the function.)