JavaScript Try..Catch


JavaScript Errors - Try and Catch

The try...catch statement is representing a block of statements. The block is used to try expressions, and specify a response if an exception is thrown.

The try statement is testing a code block for errors.

The catch statement is where you take care of and handle the error.

The throw statement is where you can create custom errors.

The finally statement executes code after try and catch. This is done regardless of the result.

JS JavaScript - JavaScript Errors - Invalid or unexpected token

try {
    eval('alert("Hello bumblebee)');
}
catch(error) {
    alert(error);
    // Result: SyntaxError: Invalid or unexpected token
}

Learn more about JavaScript Errors

Some exception messages might vary depending on the browser being used.


JavaScript - Finally

The finally statement can be used for closing a resource.

JS JavaScript - Try..Catch - Finally

openTheFileReader();
 
try {
// Write the file to disk.
    writeFileToDisk(data);
}
finally {
    closeTheFileReader(); 
    // Close the resource
}

Learn more about JavaScript Debugging Learn more about JavaScript Developer Tools

Error Name Values

There are six different values that can be returned by the name property for an error.


EvalError That creates an instance that represents an error that occurs regarding the global function eval().

InternalError That creates an instance that represents an error that occurs when an internal error in the JavaScript engine is thrown.

RangeError That creates an instance that represents an error that occurs when a numeric variable or parameter is outside of its valid range.

ReferenceError That creates an instance that represents an error that occurs when de-referencing an invalid reference.

SyntaxError That creates an instance that represents a syntax error that occurs while parsing code in eval().

TypeError That creates an instance that represents an error that occurs when a variable or parameter is not of a valid type.

URIError That creates an instance that represents an error that occurs when encodeURI() or decodeURI() are passed invalid parameters.



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JS JavaScript: Errors

There will be errors in the code. It is good practice to handle exceptions/errors.

Exceptions are a type of error that occurs during the execution of an application. Errors should be logged. Sometimes it is possible to recover a bug and proceed.
Other cases the user should get inform....

JS JavaScript: Developer Tools

Developer Tools are tools that are a part of most modern web browsers.

Every Web Developer should know how to use the tools. The tools do a range of things, from inspecting currently-loaded HTML, CSS and JavaScript to showing which assets the page has requested and how long they took to l....

JS JavaScript: Switch

The switch statement evaluates an expression and match the expression's value to a case clause.

A switch statement can replace multiple if checks.
It gives a more descriptive way to compare a value with multiple variants.

JS JavaScript: Hoisting

JavaScript hoisting is basically that declarations are moved to the top of your code.

Actually your function and variable declarations are added to memory during the compile phase.
And they stay exactly where you typed them in your code.


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JavaScript is one of the 3 core language technologies of the World Wide Web that all web developers must learn:

1.      HTML to define the content of web pages.

2.      CSS to specify the layout of web pages.

3.      JavaScript to program the behavior of web pages.

JavaScript is a scripting or programming language that allows you to implement complex things on web pages. Every time a web page does more than just sit there and display static information for you to look at, displaying timely content updates, interactive maps, animated 2D/3D graphics, scrolling video jukeboxes, etc. − you can bet that JavaScript is probably involved.


The benefits of using JavaScript are:

1.      You can validate user input before sending the page off to the server. This saves server traffic, which means less load on your server.

2.      Immediate feedback to the visitors − They don't have to wait for a page reload to see if they have forgotten to enter something.

3.      Increased interactivity − You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard.

4.      Richer interfaces − You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.


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Update Conference Prague

Update Conference Prague is the biggest developer conference in the Czech Republic. The conference is offering sessions delivered by the top experts from all around the world. Their goal is to inspire the attendees and enrich their knowledge.

Troy Hunt

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W3Schools

W3Schools.com is a great education Web Site for learning web technologies. On W3Schools you may find well organized basic to advanced tutorials and references.

Scott Hanselman

Learn about Web Technologies and new trends from Scott Hanselman. Scott Hanselman is an author of developer books and he is an engaged speaker that usually talks about the Microsoft stack. You may meet Scott on conferences around the world.

Developer Week

DeveloperWeek is one of the world’s largest developer conferences. Developer Week focus on new dev technologies, the conference have talks and workshops for newbies and experienced audience. You can attend on a Developer Week conference different places in Nothern America.


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Searching for bugs and fixing them is called code debugging. The bugs might be difficult to diagnose and therefore it is important to have a good approach to find and fix the bugs effectively. Bugs in the code might be syntax errors or logical errors. Sometimes nothing happens when the code contains bugs and there is few indications where to search. Modern web browser includes a powerful suite of developer tools. The tools do a range of things...

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