Javascript-Error Handling

Javascript-Error Handling

An error in JavaScript is an object and which is later thrown to halt the program.

you want to create a new error in JavaScript we call the appropriate constructor function.

Example:

Create a new, generic error.

const err = new Error("Something bad happened!");
creating an error object it is also possible to omit the new keyword:
const err = Error("Something bad happened!");

The error object presents three properties:

• message: a string with the error message.
• name: the error’s type.
• stack: a stack trace of functions execution.

Many types of errors in JavaScript:

• Error
• EvalError
• InternalError
• RangeError
• ReferenceError
• SyntaxError
• TypeError
• URIError

All these error types are actual constructor functions(new error object).

 An example of TypeError :

const name = "Jules";
name = "Caty";

// TypeError: Assignment to constant variable.

example of SyntaxError :

misspell language keywords

va x = '33';

// SyntaxError: Unexpected identifier

OR

Use reserved keywords in wrong places: await outside of an async function.

function wrong(){
    await 99;
}

wrong();

// SyntaxError: await is only valid in async function

built-in errors:

• DOMException
• DOMError: deprecated and no longer used today.

Family of errors related to Web APIs.

document.body.appendChild(document.cloneNode(true));

The result:

Uncaught DOMException: Node.appendChild: May not add a Document as a child