But the error "x is not defined" results from ..Stuff(x) in setInterval('repeatingStuff(x)',5000). How can the parameter between the two functions be passed within the setInteval bit?
> setInterval('repeatingStuff(x)',5000). How can the parameter between the
I thought I had tried this already but I must have simply got the quoting wrong. Of course, this works:
setInterval('repeatingStuff("' + x + '")',5000);
> But the error "x is not defined" results from ..Stuff(x) in
> setInterval('repeatingStuff(x)',5000). How can the parameter between the
> two functions be passed within the setInteval bit?
x must be in the scope of the second function. Therefore, you should define repeatingStuff inside the initialFunction:
function initialFunction(x){
alert(x);
function repeatingStuff(x){
alert(x);
}
setInterval(repeatingStuff,5000);
}
or shorter:
function initialFunction(x){
alert(x);
setInterval( function(x){
alert(x);
}, 5000);
}
You should pass a function to setIntervall/Timeout, instead of a code to be evaluated each time (slow & buggy).
Another alternative is to use bind() or other functions, to return a function which calls repeatingStuff with the needed parameters:
function repeatingStuff(){...}
function initialFunction(x){
alert(x);
setInterval( repeatingStuff.bind(this, x), 5000);
Andreas Bergmaier wrote:
> Tuxedo schrieb:
>> How can a simple string parameter be passed between two functions while
>> inside a setInterval call? For example:
>> function initialFunction(x){
>> alert(x);
>> setInterval('repeatingStuff(x)',5000);
>> }
>> function repeatingStuff(x){
>> alert(x);
>> }
>> ...
>> But the error "x is not defined" results from ..Stuff(x) in
>> setInterval('repeatingStuff(x)',5000). How can the parameter between the
>> two functions be passed within the setInteval bit?
> x must be in the scope of the second function.
In the scope _chain_.
> Therefore, you should define repeatingStuff inside the initialFunction:
> function initialFunction(x){
> alert(x); ^
^--------------'
> function repeatingStuff(x){
^
> alert(x); |
^--------------'
> }
> setInterval(repeatingStuff,5000);
> }
> or shorter:
> function initialFunction(x){
> alert(x); ^
^--------------'
> setInterval( function(x){
> alert(x); ^
^------------'
> }, 5000);
> }
This does not work, because in the context of the function (referred by `repeatingStuff'), `x' is bound to the inner function's argument `x' (which is not passed a useful value from the DOM implementation anyway) and not to that of the inner function's definition context. Please test before you post, or clearly mark code as untested.
> You should pass a function to setIntervall/Timeout, instead of a code to
> be evaluated each time (slow & buggy).
The function code also will have to be evaluated each time. But it is true that evaluating the string value as a Program is less efficient and more error-prone than that.
> Another alternative is to use bind() or other functions, to return a
> function which calls repeatingStuff with the needed parameters:
> function repeatingStuff(){...}
> function initialFunction(x){
> alert(x);
> setInterval( repeatingStuff.bind(this, x), 5000);
> }
This works in implementations of ECMAScript 5.x or where you have a suitable scripting framework that emulates Function.prototype.bind(), but it is unnecessarily inefficient by comparison.
PointedEars
--
> If you get a bunch of authors […] that state the same "best practices"
> in any programming language, then you can bet who is wrong or right...
Not with javascript. Nonsense propagates like wildfire in this field.
-- Richard Cornford, comp.lang.javascript, 2011-11-14
> Andreas Bergmaier wrote:
>> Tuxedo schrieb:
>>> How can a simple string parameter be passed between two functions while
>>> inside a setInterval call?
> This does not work, because in the context of the function (referred by
> `repeatingStuff'), `x' is bound to the inner function's argument `x' (which
> is not passed a useful value from the DOM implementation anyway) and not to
> that of the inner function's definition context.
I'm sorry, I forgot the essential thing when copying the example code :-(
@Tuxedo: The thing is to have only one variable "x". The code should be
function initialFunction(x){
alert(x);
setInterval( function(){
alert(x);
}, 5000);
}
>> Another alternative is to use bind() or other functions, to return a
>> function which calls repeatingStuff with the needed parameters
> This works in implementations of ECMAScript 5.x or where you have a suitable
> scripting framework that emulates Function.prototype.bind(), but it is
> unnecessarily inefficient by comparison.
Is it? Unnecessarily in this case, yes, but if you have defined "repeatingStuff" elsewhere it is imho much more elegant than coding
var x;
setInterval( function(){
doRepeatingStuffWith(x);
Andreas Bergmaier wrote:
> Thomas 'PointedEars' Lahn schrieb:
>> Andreas Bergmaier wrote:
>>> Another alternative is to use bind() or other functions, to return a
>>> function which calls repeatingStuff with the needed parameters
>> This works in implementations of ECMAScript 5.x or where you have a
>> suitable scripting framework that emulates Function.prototype.bind(), but
>> it is unnecessarily inefficient by comparison.
> Is it? Unnecessarily in this case, yes, but if you have defined
> "repeatingStuff" elsewhere it is imho much more elegant than coding
> Andreas Bergmaier wrote:
>> Thomas 'PointedEars' Lahn schrieb:
>>> Andreas Bergmaier wrote:
>>>> Another alternative is to use bind() or other functions, to return a
>>>> function which calls repeatingStuff with the needed parameters
>>> This works in implementations of ECMAScript 5.x or where you have a
>>> suitable scripting framework that emulates Function.prototype.bind(), but
>>> it is unnecessarily inefficient by comparison.
>> Is it? Unnecessarily in this case, yes, but if you have defined
>> "repeatingStuff" elsewhere it is imho much more elegant than coding
> That is not even equivalent in the first place. Clearly you do not
> understand bind(). Please refrain from recommending it until you do.
I do, and I never said it was to be equivalent. Of course bind() needs a context to set, dereferences x, and builds a new function. That even could be useful (I'm not sure what the OP needs), so why shouldn't I mention it as an alternative?
In comp.lang.javascript message <jh6g5k$bf...@news.albasani.net>, Sat,
11 Feb 2012 20:39:32, Tuxedo <tux...@mailinator.com> posted:
>Tuxedo wrote:
>[...]
>> setInterval('repeatingStuff(x)',5000). How can the parameter between the
>I thought I had tried this already but I must have simply got the quoting
>wrong. Of course, this works:
>setInterval('repeatingStuff("' + x + '")',5000);
That will use the value of x at call time, if x is simple or an
expression.
Another way is to pass x as a global variable; or, perhaps more clearly,
as a property of a global Object reserved and named, or otherwise
suitable, for the purpose. Actually, repeatingStuff is such an Object.
That eliminates conversions to/from String, which may be inexact.
-- (c) John Stockton, Surrey, UK. ?...@merlyn.demon.co.uk Turnpike v6.05 MIME.
Web <http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
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