Question

There is a script error in the function definition below

function foo () {
    try {
        var bar = function() {
            ERROR
        }

    } catch (exception) {
        console.debug("exception");
    }
}


foo();

But the catch failed as the bar function is not executed. Is it possible to catch those error with really running the function?

Thanks.

Answer 1

That’s not possible.

Only Synrax errors are caught without calling the function. Other errors, such as the Reference error, are dependent on when they’re called. It’s not possible to determine whether a function is going to throw a ReferenceError or not.

Example:

function foo() {
    alert(bar);
}
// If you call bar() at this point:  ReferenceError: 'bar' is not defined
// However, the variable may simply be defined later:
var bar = 'existent';
// bar():  alerts "existent"