How to use try catch throw in JavaScript to handle exceptions

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Using try catch throw in JavaScript to handle exceptions

Define exceptions in JavaScript

(1) EvalError: An error occurs in the eval () function.

(2) RangeError: A number value is greater then or less then the number that can be represented in Javascript (Number.MAX_VALUE and Number.MIN_VAKUE).

(3) ReferenceError: An illegal reference is used.

(4) SyntaxError: A syntax error occus inside of an eval () function call. All other syntax error are reorted by the browser and cannot be handled with a try...catch statement.

(5) TypeError. A variables type is unexpected. 6.URIError. An error ocuurs in the encodeURI () or the decodeURI () function.

The code is as follows:

Function CreateError () {throw new Error ("Created error by custom.");} try {/ / throw an error from a function just want to see the call stack in firefox. CreateError ();} catch (error) {var errorMsg = ("Message:" + error.message + "\ n"); if (typeof (error.stack)! = undefined) {/ / FF errorMsg + = ("Line Number:" + error.lineNumber + "\ n"); errorMsg + = ("File Name:" + error.fileName + "\ n"); errorMsg + = ("Stack Trace:\ n" + error.stack + "\ n") } else {/ / IE errorMsg + = ("Description:" + error.description + "\ n"); errorMsg + = ("Number:" + error.number + "\ n");} alert (errorMsg);} finally {/ / alert ("End try catch.message from finally block.");}

And in our code, Error.message is supported by both IE and FireFox, while IE supports description and number attributes.

FF supports fileName lineNumber and stack attributes. Because Javascript is a weakly typed language, you can only catch once in the catch section. Languages like C # cannot write multiple exception of different types of catch,catch. However, similar functions can be implemented in the instanceof ErrorType way. The code is as follows:

Try {/ / SyntaxError / / eval ("alert a"); / / Custom Error throw new Error ("An error occured.");} catch (error) {if (error instanceof SyntaxError) {alert ("SyntaxError");} else if (error instanceof EvalError) {alert ("EvalError");} else if (error instanceof RangeError) {alert ("RangeError");} else if (error instanceof ReferenceError) {alert ("ReferenceError") } else if (error instanceof TypeError) {alert ("TypeError");} else if (error instanceof Error) {alert ("Custon Error");} alert (error.message);}

For the assert () aspect of JavaScript, we can take a look at the following code:

Function assert (bCondition, sErrorMsg) {if (! bCondition) {alert (sErrorMsg); throw new Error (sErrorMsg);}} these are all the contents of the article "how to handle exceptions using try catch throw in JavaScript". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!