如何判断Javascript错误是否为“阻止”？

Question

Is there such a thing as blocking vs non blocking Javascript errors?

What I mean is that I've seen my site report some errors, but the process involved still completes successfully (as far as I can tell). These errors include: TypeError: undefined is not an object (evaluating 'e.nodeName.toLowerCase') TypeError: e.nodeName is undefined (these are always from my general JQuery library file)

These are what I mean by 'non-blocking' errors, since the scripts involved seem to complete successfully.

If there is such a thing as blocking v non-blocking, what is the correct terminology for it, and how can I tell the difference between the 2 (eg so that I can prioritise investigating blocking errors)?

Thanks

Answer 1

Whenever

throw Error;

The exception bubles up the function stack. If it reaches the end of it, it throws an uncaught (=unexpected) exception. This halts the complete program as its unlikely to work properly anymore.

However it can be catched (=expected exception):

try{
 someerrorproducingfunc();
 //continue after success
}catch(e){
 //continue after error
 console.error(e);
}
//continue after error+success

So the code proceeds ( leaving out the continue after sucess part). However, if you use console.error it logs sth that looks like an error.

ressource: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/throw

---

Note that Error is just an object constructor in js:

new Error("test");

While throw throws an exception ...

Answer 2

No. All un-caught error are blocking, they will end the execution of the entire call stack. However, an error that happens after various operation will not revert back to a situation like before. Making an AJAX call, and then having an undefined error will not cancel the call for example. Demo:

 (function () { "use strict"; let a = 5; console.log(a); // 5 setTimeout(function () { console.log(a); // 10 // will execute because it is a fresh stack // the variable a is 10 despite and not 12 because it happened after }, 250); const withError2 = function () { a = 10; axz = 2; // Error a = 12; // never executes because it comes after the error } withError2(); console.log(a); // never executes because it comes after the error }());