CODEWITHSUNDEEP
javascript
bethesdaboys
bethesdaboys

Reputation: 1827

Halting JavaScript program operation upon error condition?

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
    }
}

Upvotes: 0

Views: 113

Answers (4)

Paco Valdez
Paco Valdez

Reputation: 1975

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.

Upvotes: 0

themhz
themhz

Reputation: 8424

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;
    }
}

Upvotes: 0

Phil Klein
Phil Klein

Reputation: 7514

You must re-throw the exception:

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

Upvotes: 1

Rob W
Rob W

Reputation: 349252

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.

Upvotes: 2

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