CODEWITHSUNDEEP
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Rocky111
Rocky111

Reputation: 255

Javascript stop execution abort or exit

if(a.value==1 && b.value==2)
{
    try{callFunc()  }catch(e) {} 
}
frm.submit();

Inside function callFunc(), what do I have to write so that execution completely stops? It should not execute frm.submit();

function callFunc()
{
    //stop execution here -- ensure it won't execute fm.submit()
}

Upvotes: 5

Views: 34578

Answers (8)

joser
joser

Reputation: 113

To kill the execution of a JS script use:

system.stop()

Upvotes: 0

steveluscher
steveluscher

Reputation: 4228

I understand what you are trying to do. You don't want to kill the Javascript interpreter, you just want to prevent the form submission from proceeding.

HTML

<form id="myForm">
  …
</form>

Javascript

// Setup…
var frm = document.getElementById('myForm'),
    a = { value: 1 },
    b = { value: 2 };

// Can change this code
var callFunc = function() {
    // Throwing will do nothing here, since
    // exceptions are being caught in a try/catch

    // Instead, let's overwrite the submit handler with one that
    // will cancel the form submission, then restore the old handler
    var oldSubmitHandler = frm.submit;
    var killHandler = function(e) {
        // Prevents the submission
        e.preventDefault();

        // Restores the old handler
        frm.submit = oldSubmitHandler;
    };
    frm.submit = killHandler;
};

// Can't change any of this code
if(a.value==1 && b.value==2)
{
    try { callFunc() } catch(e) { } 
}

// Want to stop this from happening
frm.submit();

See it in action: http://jsfiddle.net/3A7xC/

Upvotes: 1

Shebin
Shebin

Reputation: 3468

You can abort javascript execution using throw:

if(a.value==1 && b.value==2){
    try{callFunc()  }catch(e) {} 
}
frm.submit();

function callFunc() {
    throw "stop execution";
}

Upvotes: -1

eswald
eswald

Reputation: 8406

As you've discovered, aborting JavaScript almost always involves exceptions. If you truly can't change the wrapper, then you might have to resort to something a bit more extreme. One (evil) way to kill the script is to convince the browser that it's taking too long, by running an infinite loop:

function callFunc()
{
    //stop execution here
    var n = 1;
    while (n) {
        n += 1;
    }
}

Modern browsers will let the user kill the script after a while. Granted, it will make your site seem broken, but that should give you the leverage you need to get a better API in place.

If the busy-loop is too extreme, you could replace the simple addition with a plugin-based sleep, or perhaps a synchronous network request that takes an extremely long time, wrapped in its own try/catch safety net.

Upvotes: 1

PHearst
PHearst

Reputation: 771

So the inside of the callFunc is the only thing you can change? How about this:

callFunc(){
    frm.submit(function() {
      alert('this should not submit');
      return false;
  });   
}

Upvotes: 0

Pranay Rana
Pranay Rana

Reputation: 176886

Better one is 

function Abort()
{
   throw new Error('This is not an error. This is just to abort javascript');
}

than from any where call this 

try
{
    for(var i=0;i<10;i++)
    {
         if(i==5)Abort();
    }
} catch(e){}

For you 

function callFunc()  
{      
    //stop execution here 
    Abort();

    } 

//code from where you are going to call

try
{
  if(a.value==1 && b.value==2)    
  {        
   callFunc()   
  }    
  frm.submit(); 
}
catch(e) {}

Upvotes: 4

RobG
RobG

Reputation: 147343

Lots of answers, one more for fun.

You can put the code in a function, have the try block throw an error, then return from the catch clause:

function foo() {
    var a = {value:1};
    var b = {value:2};

    if(a.value==1 && b.value==2) {

       try {
          callFunc();

       } catch(e) {
          alert(e.message);
          return;
       }
    }
    alert('error didn\'t stop me!');
}



function callFunc() {
      throw new Error('This is an error.');  
}

Otherwise you can set a flag in the catch block and test for it immediately afterward before going any further. Or take one of the other answer's options.

Upvotes: 0

safrazik
safrazik

Reputation: 1601

Better way is this:

if(a.value==1 && b.value==2)
{
  try{
    callFunc();  
    frm.submit();
  }
   catch(e) {
    // stop execution
  } 
}

If an exception is thrown in function callFunc, the frm.submit(); line would not be executed. Instead, it will skip to the catch clause

Upvotes: 0

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