Exit the loop suddenly

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Exit the loop suddenly

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#1 by (2 votes)
#2 by (0 votes)
#3 by (-1 votes)

2

Let's imagine the following code:

function FazAlgoTrabalhoso(parametro1, parametro2, parametro3){
//Algo trabalhoso aqui
}

var i;
for(i=0;i<=coisas.length;i++){
  //"coisas" é um array já preenchido
  FazAlgoTrabalhoso(coisas[i].algo1, coisas[i].algo2, coisas[i].algo3);
}

$( "#botao_para_cancelar" ).click(function() {
  //Algo para cancelar...
});

Let's say that the "things" array has 100 positions, so the for loop run 100 times, that is, it will do "something laborious" 100 times.
Let's also consider that "WorkLoad" takes about 5 seconds to run completely.

My question is: How do I manage the cancellation of "WorkOnLine"? For example, if it has already run 50 times, how can I cancel the subsequent executions through a button? I did not succeed in my attempts and it always ends up running the whole loop ....

javascript jquery

asked by anonymous 02.03.2017 / 14:01

3 answers

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score 2 · Answer 1

Your biggest problem is that ...

var i;
for(i=0;i<=coisas.length;i++){
  FazAlgoTrabalhoso(coisas[i].algo1, coisas[i].algo2, coisas[i].algo3);
}

... is a synchronous process, which means that JavaScript will not stop to check if an event has been triggered, such as the click of a button.

You need to convert this function to operate asynchronously:

function FazAlgoTrabalhosoAsync(x) {
  if (!x) x = 0;

  FazAlgoTrabalhoso(coisas[i].algo1, coisas[i].algo2, coisas[i].algo3);

  if (x < coisas.length) 
      setTimeout(function() {FazAlgoTrabalhosoAsync(x + 1);}, 1);
}

FazAlgoTrabalhosoAsync();

setTimeout() causes the function to be called in the future. In the meantime, events can be intercepted, and an interrupt flag marked true :

var tenhoQueParar = false;

$( "#botao_para_cancelar" ).click(function() {
  tenhoQueParar = true;
});

function FazAlgoTrabalhosoAsync(x) {
  if (!x) x = 0;

  FazAlgoTrabalhoso(coisas[i].algo1, coisas[i].algo2, coisas[i].algo3);

  if ((x < coisas.length) && !tenhoQueParar) 
      setTimeout(function() {FazAlgoTrabalhosoAsync(x + 1);}, 1);
}

FazAlgoTrabalhosoAsync();

score 0 · Answer 2

I have decided as follows:

    function FazAlgoTrabalhoso(parametro1, parametro2, parametro3){
    //Algo trabalhoso aqui

    var timer = window.setInterval(function(){
    var pagina = $$('.page').data('page');
    console.log("Estou na página: "+pagina);
    if(pagina != 'preview'){
        //Rotina de cancelamento...

        console.log('Abortado');
        clearInterval(timer);
    }
 },1000);
}

That is, I changed the scope. Instead of canceling at the click of a button, I was able to monitor when the user leaves the page. In this, I cancel the process.

score -1 · Answer 3

To exit the loop, just add the break

var cancelar = false;
function FazAlgoTrabalhoso(parametro1, parametro2, parametro3){
//Algo trabalhoso aqui
}

var i;
for(i=0;i<=coisas.length;i++){
  //"coisas" é um array já preenchido
  FazAlgoTrabalhoso(coisas[i].algo1, coisas[i].algo2, coisas[i].algo3);
  if (cancelar){
      break;
  }
}

$( "#botao_para_cancelar" ).click(function() {
  cancelar = true;
});