Javascript - can you throw an object in an Error?

Question

Is it possible to throw an object using Error? In the example below the console shows undefined.

try {     throw Error({foo: 'bar'}); } catch (err) {     console.log(err.message.foo); } 

Answer 1

You can throw your own object, and associate an Error instance with it:

try {   // ...   throw {     foo: "bar",     error: new Error()   }; 

The throw statement is not picky, but the Error() constructor is. Of course, if you throw something that's not an Error, it's only useful if the catching environment expects it to be whatever you throw.

Having the Error object as part of your custom thrown value is useful because a constructed Error instance has (in supporting browsers, which currently seems to be essentially all of them) an associated stack trace.

Answer 2

You could try converting the object to a JSON string and then parsing the error message into a JSON object in the catch statement:

try {     throw Error(JSON.stringify({foo: 'bar'})); } catch (err) {     console.log(JSON.parse(err.message).foo); }