JavaScript: Send function as a parameter to another function (callbacks) JavaScript: Send funzjoni bħala parametru ieħor għall-funzjoni (callbacks)

Posted on 29. Posted on 29. Jul, 2009 by Dragos in Coding , JavaScript & Ajax Lulju, 2009 mill Dragos fl-Kodifika, JavaScript & Ajax

I'm sure you've seen a lot of code where functions are send as parameters, usually working as function callbacks eg: Jien ċert li inti stajt tidher ħafna ta 'kodiċi fejn il-funzjonijiet huma jibagħtu bħala parametri, normalment taħdem bħala callbacks funzjoni eż:

 setTimeout(function () { alert('test'); },1000); (setTimeout funzjoni () (allert test ( "");), 1000); 

But how does the function setTimeout execute the passed function as a parameter? Imma kif ma 'l-setTimeout funzjoni jesegwixxu l-funzjoni għadda bħala parametru? The answer is simple, but I need to provide you an example to understand it It-tweġiba hija sempliċi, iżda għandi bżonn biex jagħtuk eżempju ħalli jifhmuha

Let's create a simple function, accepting two parameters: first a boolean value, the second – a function. Let's toħloq funzjoni sempliċi, taċċetta ż-żewġ parametri: l-ewwel valur Boolean, it-tieni - funzjoni. Our function will analyze the boolean parameter and in case the value is true , the function passed as a parameter will be executed. Funzjoni tagħna se janalizza l-parametru Boolean u fil-każ il-valur huwa veru, il-funzjoni għadda bħala parametru ser jiġu esegwiti.

 function simpleFunc(bool,func) { funzjoni simpleFunc (bool, funzjoni) ( 
     if(bool) func(); jekk (bool) funzjoni (); 
 } ) 

As you notice, we add parentheses after the name of the second parameter, because we'll treat it as a function. Kif tinnota, aħna żid-parentesi wara l-isem tal-parametru tieni, għaliex aħna ser titratta dan bħala funzjoni. And that's te whole secret. U li l-sigrieti kollha te.

Now that is how we will use the simpleFunc function: Issa li hija kif se nużaw il-funzjoni simpleFunc:

 simpleFunc(false,function() { alert('Yupee!'); }; // this won't alert anything, because the boolean parameter is false simpleFunc (falza, funzjoni () (allert Yupee ( "!");); / / dan ma allert xejn, minħabba li l-parametru Boolean hija falza 
 //example two / / eżempju żewġ 
 simpleFunc(true,function() { alert('Yupee!'); }); // this will alert Yupee! simpleFunc (veru, funzjoni () (allert Yupee ( "!");)); / / dan se twissija Yupee! 

Wish you luck! Nixtiqilkom xortih!

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