Halting JavaScript program operation upon error condition?

Question

So in my app when a particular condition occurs, I want to display an alert and then stop program execution. I read somewhere that this can be done with a throw() but I'm unable to make that work.

Here's what I've tried:

function check_for_error(data) {
    try {
        if ( <error condition> ) { 
            throw "error"; 
        }
    } catch(e) {
            alert('error occured'); 
                // I want program execution to halt here but it does not, 
                // it continues within the calling code
    }
}

You can try throwing error from the catch block and then handling it in the callee method. And essentially exit. — Sid
– Sid, Commented Dec 16, 2011 at 19:10

Rob W · Accepted Answer · 2011-12-16 19:10:12Z

2

You should throw another error in the catch block. Or not catch the initial error at all.

Currently, the following happens:

<error condition me>
throw "error"
catch error and  Show alert

To "halt" the execution, you have to add throw e after the alert (in the catch block):

catch(e) {
    alert('error occurred');
    throw e;
}

If your function is called from within another try-catch block, you also have to apply a similar mechanism to that block.

answered Dec 16, 2011 at 19:10

Rob W

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Comments

Phil Klein · Accepted Answer · 2011-12-16 19:11:05Z

1

You must re-throw the exception:

...
catch(e) {
    alert('error occurred');
    throw(e);
}

answered Dec 16, 2011 at 19:11

Phil Klein

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1 Comment

bethesdaboys Over a year ago

Ok got it to work by doing the above, then in the calling function putting the call in a try / catch, with the catch empty. Thanks.

themhz · Accepted Answer · 2011-12-16 19:13:25Z

0

and also you can

function check_for_error(data) {
    try {
       //WHEN ERROR OCCURES
    } catch(e) {
            alert('error occured'); 
                // I want program execution to halt here but it does not, 
                // it continues within the calling code
            throw(e);
            return;
    }
}

answered Dec 16, 2011 at 19:13

themhz

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Comments

Paco Valdez · Accepted Answer · 2011-12-16 19:15:49Z

0

Throw only will stop execution of synchronous rutines, For example if you made an asynchronous http request it will execute the callback function regardless of a previous error.

Throw doc from w3c:

Syntax

throw exception

The exception can be a string, integer, Boolean or an object.

answered Dec 16, 2011 at 19:15

Paco Valdez

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