Error Form Java Script
Contents |
& Guides Learn the Web Tutorials References Developer Guides Accessibility Game development ...more docs Mozilla Docs javascript error object Add-ons Firefox WebExtensions Developer ToolsFeedback Get Firefox help Get web development javascript error handling help Join the MDN community Report a content problem Report a bug Search Search Languages Català javascript try catch (ca) Deutsch (de) Español (es) Français (fr) Bahasa Indonesia (id) 日本語 (ja) 한국어 (ko) Polski (pl) Português (do Brasil) (pt-BR) Русский (ru) 中文 (简体) (zh-CN) 正體中文 (繁體) (zh-TW) javascript throw error Add a translation Edit Advanced Advanced History Print this article MDN Web technology For developers JavaScript JavaScript reference Standard built-in objects Error Your Search Results ariyankhan josephmcasey AlexanderFradiani fscholz mondwan SphinxKnight janosch-x davidchase Mingun shawnacscott Sheppy ethertank Nickolay evilpie trevorh teoli davidbourguignon secoif DomenicDenicola dgchurchill timemachine3030 Sevenspade Potappo Sephr Brettz9 Mgjbot Allanbonadio Ptak82 JustinLudwig
Fix Javascript Error
Error In This Article SyntaxParametersDescriptionError typesPropertiesMethodsError instancesPropertiesStandard propertiesVendor-specific extensionsMicrosoftMozillaMethodsExamplesThrowing a generic errorHandling a specific errorCustom Error TypesSpecificationsBrowser compatibilitySee also The Error constructor creates an error object. Instances of Error objects are thrown when runtime errors occur. The Error object can also be used as a base object for user-defined exceptions. See below for standard built-in error types. Syntax new Error([message[, fileName[, lineNumber]]]) Parameters message Optional. Human-readable description of the error. fileName Optional. The value for the fileName property on the created Error object. Defaults to the name of the file containing the code that called the Error() constructor. lineNumber Optional. The value for the lineNumber property on the created Error object. Defaults to the line number containing the Error() constructor invocation. Description Runtime errors result in new Error objects being created and thrown. This page documents the use of the Error object itself and its use as a constructor function. For a list of properties and methods inherited by Error instances, see Error.prototype.
As promised, we're going to take a closer look at the Error object that gets passed into the catch clause to see just what we can extract from it in
Javascript Alert
an event of an error. The Error object in all browsers support the javascript exception following two properties: name: The name of the error, or more specifically, the name of the constructor function the error page javascript error belongs to. message: A description of the error, with this description varying depending on the browser. try{ document.body.filters[0].apply() } catch(e){ alert(e.name + "\n" + e.message) } Demo: Six possible values can https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error be returned by the name property, which as mentioned correspond to the names of the error's constructors. They are: Error Name Description EvalError An error in the eval() function has occurred. RangeError Out of range number value has occurred. ReferenceError An illegal reference has occurred. SyntaxError A syntax error within code inside the eval() function has occurred. All other syntax errors are not caught http://www.javascriptkit.com/javatutors/trycatch2.shtml by try/catch/finally, and will trigger the default browser error message associated with the error. To catch actual syntax errors, you may use the onerror event. TypeError An error in the expected variable type has occurred. URIError An error when encoding or decoding the URI has occurred (ie: when calling encodeURI()). This level of detail may be useful when you wish to sniff out a specific type of error in your catch clause. In the below, no DIV on the page exists with ID="mydiv". 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 (e.name.toString() == "TypeError"){ //evals to true in this case //do something } } Ok, so maybe it's not that useful most of the time, but you just never know. Throwing your own errors (exceptions) Instead of waiting for one of the 6 types of errors above to occur before control is automatically transferred from the try block to the catch block, you can also explicitly throw your own exceptions to force that to happen on demand. Th
resources Windows Server 2012 resources Programs MSDN subscriptions Overview Benefits Administrators Students Microsoft Imagine Microsoft Student Partners ISV Startups TechRewards Events Community https://msdn.microsoft.com/en-us/library/dww52sbt(v=vs.94).aspx Magazine Forums Blogs Channel 9 Documentation APIs and reference Dev centers Retired content Samples We’re sorry. The content you requested has been removed. You’ll be auto http://eloquentjavascript.net/1st_edition/chapter5.html redirected in 1 second. JavaScript Language Reference JavaScript Reference JavaScript Objects JavaScript Objects Error Object Error Object Error Object ActiveXObject Object Array Object ArrayBuffer Object arguments javascript error Object Boolean Object DataView Object Date Object Debug Object Enumerator Object Error Object constructor Property (Error) prototype Property (Error) description Property (Error) message Property (Error) name Property (Error) number Property (Error) stack Property (Error) stackTraceLimit Property (Error) toString Method (Error) valueOf Method (Error) Float32Array Object Float64Array Object Function Object Global Object Int8Array Object error form java Int16Array Object Int32Array Object Intl.Collator Object Intl.DateTimeFormat Object Intl.NumberFormat Object JSON Object Map Object Math Object Number Object Object Object Promise Object Proxy Object Reflect Object RegExp Object Regular Expression Object Set Object String Object Symbol Object Uint8Array Object Uint8ClampedArray Object Uint16Array Object Uint32Array Object VBArray Object WeakMap Object WeakSet Object WinRTError Object TOC Collapse the table of content Expand the table of content This documentation is archived and is not being maintained. This documentation is archived and is not being maintained. Error Object (JavaScript) Contains information about errors.Syntax Copy errorObj = new Error() errorObj = new Error([number]) errorObj = new Error([number[, description]]) ParameterserrorObjRequired. The variable name to which the Error object is assigned. The variable assignment is omitted when you create the error using a throw statement.numberOptional. Numeric value assigned to an error. Zero if omitted.descriptionOptional. Brief string that describes an error. Empty string if omitted.RemarksWhenever a run-time error occurs, an instance of the Error object
as expected is a good start. Making your programs behave properly when encountering unexpected conditions is where it really gets challenging. ¶ The problematic situations that a program can encounter fall into two categories: Programmer mistakes and genuine problems. If someone forgets to pass a required argument to a function, that is an example of the first kind of problem. On the other hand, if a program asks the user to enter a name and it gets back an empty string, that is something the programmer can not prevent. ¶ In general, one deals with programmer errors by finding and fixing them, and with genuine errors by having the code check for them and perform some suitable action to remedy them (for example, asking for the name again), or at least fail in a well-defined and clean way. ¶ It is important to decide into which of these categories a certain problem falls. For example, consider our old power function:function power(base, exponent) { var result = 1; for (var count = 0; count < exponent; count++) result *= base; return result; } ¶ When some geek tries to call power("Rabbit", 4), that is quite obviously a programmer error, but how about power(9, 0.5)? The function can not handle fractional exponents, but, mathematically speaking, raising a number to the halfth power is perfectly reasonable (Math.pow can handle it). In situations where it is not entirely clear what kind of input a function accepts, it is often a good idea to explicitly state the kind of arguments that are acceptable in a comment. ¶ If a function encounters a problem that it can not solve itself, what should it do? In chapter 4 we wrote the function between:function between(string, start, end) { var startAt = string.indexOf(start) + start.length; var endAt = string.indexOf(end, startAt); return string.slice(startAt, endAt); } ¶ If the given start and end do not occur in the string, indexOf will return -1 and this version of between will return a lot of nonsense: between("Your mother!", "{-", "-}") returns "our mother". ¶ When the program is running, and the function is called like that, the code that called it will get a string value, as it expected, and happily continue doing something with it. But