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Javascript Error Properties

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const myObject = {}; Error.captureStackTrace(myObject); myObject.stack // similar to `new Error().stack` The first line of the trace, instead of being prefixed with ErrorType: message, will be the result of calling targetObject.toString(). ENOTDIR (Not a directory): A component of the given pathname existed, but was not a directory as expected. finally statements .. } Works like this: The try statements are executed. How these errors are reported and handled depends entirely on the type of Error and the style of the API that is called. get redirected here

To review, the basic syntax is: throw new Error("message"); This works in all browsers and will display the error information in the same way it would any unintentional JavaScript error. See the browser compatability table below. It may throw errors, some of them we know how to process, like ValidationError. Class: RangeError# A subclass of Error that indicates that a provided argument was not within the set or range of acceptable values for a function; whether that is a numeric range,

Javascript Error Message

So in the example above, there should be throw new BadAgeError("Invalid age"). If all is fine, then all is fine. Standard   ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'Error.prototype.message' in that specification.

The function example would look like: try { func() } catch(e) { alert(e) } If an error occurs inside the try block, the control is passed to the catch(e) section. When trying to set its .innerHTML property, a TypeError occurs, since we're trying to assign the .innerHTML property to a null object: try{ document.getElementById("mydiv").innerHTML='Success' //assuming "mydiv" is undefined } catch(e){ if ReferenceError instances will have an error.arguments property whose value is an array containing a single element: a string representing the variable that was not defined. Define Mistakenly In the following example, the return occurs from inside try, but finally still intercepts it and executes before the control is passed to the calling code.

Methods Error.prototype.toSource() Returns a string containing the source of the specified Error object; you can use this value to create a new object. Javascript Throw New Exception By checking for the more specific error types, you get more robust error handling: try { //something that causes an error } catch (ex){ if (ex instanceof TypeError){ //handle the error The Error object can also be used as a base object for user-defined exceptions. try { new Function('throw new Error()')(); } catch (e) { console.log(e.stack); } // [email protected]:///C:/example.html line 7 > Function:1:1 // @file:///C:/example.html:7:6 try { eval("eval('FAIL')"); } catch (x) { console.log(x.stack); } // @file:///C:/example.html

Human-readable description of the error. Node Error Object Of course, you can throw any type of data that you'd like. Standard   ECMAScript 2017 Draft (ECMA-262)The definition of 'Error.prototype.message' in that specification. I got a lot of responses and follow-up questions, so I thought I'd continue the discussion by explaining a little more about how to throw your own errors.

Javascript Throw New Exception

For example, trying to create an array with -20 items (new Array(-20)). new Error(message)# Creates a new Error object and sets the error.message property to the provided text message. Javascript Error Message But anyway, leaving an exception object is dangerous. Define Inaccuracy Similar to message.

The try..catch construct itself takes several lines. http://shpsoftware.com/javascript-error/javascript-catch-error-object-properties.php The only surefire way to have all browsers display your custom error message is to use an Error object. Copyright (c) 1997-2016 JavaScript Kit. It is possible to omit catch if finally is provided: // rarely used, but valid try { .. } finally { .. } try..catch..finally and return The finally works in any Define Miscalculation

Error.prototype.stack Stack trace. Error.prototype.columnNumber Column number in line that raised this error. EvalError Creates an instance representing an error that occurs regarding the global function eval(). useful reference ECONNRESET (Connection reset by peer): A connection was forcibly closed by a peer.

Errors System Errors Class: System Error error.code error.errno error.syscall Common System Errors Errors# Applications running in Node.js will generally experience four categories of errors: Standard JavaScript errors such as: : Nodejs Throw Error if (err) { throw err; } }); } catch(err) { // This will not catch the throw! There are errors which can only be caught by try..catch, because you can't detect a possible fail until you try.

The common way to do this is demonstrated below.

Disclaimer: Any viewpoints and opinions expressed in this article are those of Nicholas C. EADDRINUSE (Address already in use): An attempt to bind a server (net, http, or https) to a local address failed due to another server on the local system already occupying that Commonly raised by fs.readdir. Eror The message passed to the constructor will also appear in the first line of the stack trace of the Error, however changing this property after the Error object is created may

These errors are almost always indicative of a broken program. It takes a variable and check it for valid age: function validateAge(age) { // age is a text to check if (age === '') return // no age is valid age For a list of properties and methods inherited by Error instances, see Error.prototype. http://shpsoftware.com/javascript-error/javascript-error-object-properties.php In the catch section we analyze the exception and process it if we are able to.

The syntax is: throw e, where e is literally anything. Thus, in Firefox 14 and later this is less of an issue. Error.prototype.message Error message. Examples Using lineNumber var e = new Error('Could not parse input'); throw e; console.log(e.lineNumber) // 2 Alternative example using error event window.addEventListener('error', function(e) { console.log(e.lineNumber); // 5 }); var e =

Defaults to the line number containing the Error() constructor invocation. Methods The global Error object contains no methods of its own, however, it does inherit some methods through the prototype chain. The number of frames captured by the stack trace is bounded by the smaller of Error.stackTraceLimit or the number of available frames on the current event loop tick. If that's not enough, you can even throw a generic Error object with custom name and message properties: throw{ name: "JavaScriptKit Error", message: "Error detected.

Technically entering a string or number less than 13 certainly doesn't constitute an exception in JavaScript, though for our purpose here, they should. Instead, you'll see the generic "exception thrown but not caught" error message. Specifications Specification Status Comment ECMAScript 1st Edition (ECMA-262) Standard Initial definition. The example below demonstrates the idea of how throw works.

Second, the browser attaches extra information to Error objects when they are thrown. So the try..catch is only the way to go. There are, however, several advantages to throwing actual Error objects instead of other object types. In Node.js, system errors are represented as augmented Error objects with added properties.

function f(a) { g(a+1) } function g(a) { notexists; } try { f(1) } catch(e) { alert(e.stack) } Unfortunately, IE does not have this property even in IE9. ENOTEMPTY (Directory not empty): A directory with entries was the target of an operation that requires an empty directory -- usually fs.unlink. Error.prototype.name Error name. Well, frankly, the antipattern of leaving exception unprocessed is more from the Java world.

A completely different way to handle errors which replaces the checking code. Changes will affect any stack trace captured after the value has been changed. Note that if string arguments were passed in with values such as "@", "(", ")" (or if in file names), you could not easily rely on these for breaking the line Otherwise, the exception is rethrown.

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