What's the difference between Error and Exception in Javascript?
JavaScript syntax
Errors and exceptions are syntactically synonymous in JavaScript. The language only implements the Error keyword (through window.Error). You may define custom errors, using the Error.constructor, which takes name and message as parameters.
JavaScript Error
There is also the line number sugar that can be used to trace bug occurrences inside the code. JavaScript only has Error. Whether you hear people talking about Exceptions or Errors, in JavaScript they refer to the same thing.
Browsers make a distinction: ReferenceError (when accessing a variable with a name that doesn't exist in the heap, or when you make a typo(more here.), TypeError is also a known JS error, more here.
JavaScript Exception
A known JavaScript Exception is DOM Exception 8. It occurs when you access an object that is not ready, such as an XMLHttpRequest that has not completed the request.
Implementation
When using try catch or try catch finally blocks, you will deal with both JavaScript Exception and Error. Code-wise the difference has no impact.
Behind the scenes, the browsers use the same window.Error constructor. An Exception is an Error instance with a name and message that contain "Exception".
Try: var myCustomError = new Error("myException", "An exception occurred.");. "Exception" is text in a string. More on Error here.
Convention
By convention, there is a difference between Error and Exception. An Error indicates a clear violation. A TypeError or ReferenceError means you are not following the language specs.
An Exception is thrown when you access an XMLHttpRequest response before it is complete. Error is a "you broke the law" shout and Exception is an "Almost there!" pad on the shoulder. Hope the analogy helps!
Based on the lecture, the Errors are thrown by JavaScript engine and exception are thrown by developer. it is only naming convention.
- JavaScript throws Errors
- Developers throws Exceptions
In technical aspect is the same structure (thing).