21, Feb 2023
Why ‘X’ + Y = ‘XY’ in TypeScript ? Expect an error

In TypeScript, when a string is concatenated with a non-string value using the “+” operator, the non-string value is implicitly converted to a string before concatenation. This is known as type coercion. This is why the expression ‘X’ + Y results in ‘XY’ instead of an error.

For example, in the following code snippet, the variable Y is of type number, but it gets implicitly converted to a string before getting concatenated with ‘X’:

let Y = 10;
let result = 'X' + Y;
console.log(result); // Output: 'X10

This behavior is not specific to TypeScript, but it’s common in many programming languages. This is because the + operator is overloaded in many languages, it can be used for both mathematical addition and string concatenation. If one operand is a string, the other is converted to a string, then concatenation is applied.

However, if you want to avoid this behavior, you can use a more explicit way of converting a non-string value to a string, such as using the String() function or the template literals \ `.

let Y = 10;
let result = 'X' + String(Y);
console.log(result); // Output: 'X10'

let result2 = `X${Y}`;
console.log(result2); // Output: 'X10'

In this way, you can avoid unexpected behavior, and also make your code more readable.

21, Feb 2023
let numInArray: number[ ] = [ ]; Gives this ERROR ” SyntaxError: Unexpected token ‘:’ “

The error “SyntaxError: Unexpected token ‘:'” is indicating that the JavaScript interpreter is encountering a colon (‘:’) in a place where it is not expected.

In this case, it appears that the issue is with the syntax of the variable declaration. In JavaScript, when you want to declare an array with a specific type of elements, you can use the type followed by [] instead of :[].

Here is an example of the correct syntax for declaring an array of numbers in JavaScript:

let numInArray: number[] = [];

or

let numInArray = [] // This will be considered as Array<any>

You can also use the Array<Type> to define the type of element which array will contain.

let numInArray: Array<number> = [];

It should fix the issue and your code should work without any error.

21, Feb 2023
Error: request entity too large

Error: request entity too large

The “request entity too large” error is typically encountered when a client (such as a web browser) sends a request to a server that is larger than the server is configured to handle. This can occur when a client is uploading a large file or sending a large amount of data in the request body.

This error can be caused by different reasons, but some of the common ones are:

  • The server’s maximum allowed request size is set too low.
  • The client is sending a file that is larger than the maximum allowed size.
  • The server-side code does not correctly handle large requests.

There are different ways to fix this problem, depending on the specific cause:

  • Increase the maximum allowed request size on the server.
  • Reduce the size of the file being uploaded by the client.
  • Handle large requests correctly in the server-side code.
  • In some cases, you may need to split the large files into smaller chunks and send them separately.

It’s also good to check the error logs of the server to get more information about the cause of the error.

21, Feb 2023
Workaround for repeatedly call Response.Redirect and returns ERR_TOO_MANY_REDIRECTS

The “ERR_TOO_MANY_REDIRECTS” error occurs when the browser detects that it is being redirected in a loop. This can happen when a web page calls the Response.Redirect method multiple times without breaking the loop.

One workaround to fix this issue is to use a flag variable to check if the page has already been redirected. If the page has been redirected, the flag variable is set and the Response.Redirect method is not called again.

Here’s an example:

bool redirected = false;

if (!redirected)
{
    redirected = true;
    Response.Redirect("newPage.aspx");
}

Another way to avoid this error is to use a Server.Transfer method instead of Response.Redirect. The Server.Transfer method transfers the execution of the current page to a new page, without the browser being aware of it.

Server.Transfer("newPage.aspx");

It’s important to note that using Server.Transfer method doesn’t change the URL in the browser and it doesn’t update the browser history.

It’s also worth checking if the redirect is necessary in the first place, and if not, remove the redirect statement.

21, Feb 2023
Failed to load resource: net::ERR_CONNECTION_RESET and Uncaught (in promise) TypeError: Failed to fetch

The error “Failed to load resource: net::ERR_CONNECTION_RESET” usually indicates that there is a problem with the network connection, and the browser is unable to establish a connection to the server to load the resource.

The error “Uncaught (in promise) TypeError: Failed to fetch” usually indicates that there is an issue with the fetch API call you are using to retrieve data from the server. This can happen due to various reasons like, issues with the server, cross-origin resource sharing (CORS) issues, or problems with the fetch call itself.

To troubleshoot these errors, you can try the following steps:

  1. Check your network connection to ensure that it is stable and there are no issues with the internet connection.
  2. Check if the server is up and running, and if there are any issues with it that might be preventing it from responding to requests.
  3. If the server is running fine and the problem is with the fetch call, check the URL and the options that you are passing to the fetch call to ensure that they are correct.
  4. If you are making a cross-origin request, check that the server is configured to handle CORS and that the appropriate headers are set on the response.
  5. Check the browser’s developer console for additional information that might help you understand the problem.
  6. Try to reproduce the error on different browsers and devices to see if the issue is specific to a certain browser or device.
  7. Try to test the API endpoint by calling it directly in the browser, making sure that the API is working fine, this will help to identify if the problem is with API or with the client side.
  8. Try to use a third-party tool like postman to test the API.

It’s important to note that these are general suggestions and the actual cause of the error may vary depending on the specific circumstances.

21, Feb 2023
notifySuccess on saveEvent not working, seeing error in console

The “notifySuccess on saveEvent not working” error can have a few different causes. Here are a couple of things you can try to troubleshoot the problem:

  1. Make sure that the notifySuccess function is being called correctly. Check that the function is being invoked with the correct parameters and that the function is defined in the same scope as the saveEvent function.
  2. Check if the notifySuccess function is defined and implemented correctly. Make sure that the function is defined and that it is performing the correct actions when it is invoked.
  3. Check if the notifySuccess function is being called after the saveEvent function has successfully completed. Make sure that the saveEvent function is successfully executing before the notifySuccess function is being called.
  4. Make sure that the notifySuccess function is being invoked with the correct context, for example, if the function is defined inside a class component, make sure it’s being called using this.notifySuccess()
  5. Check the browser console for any error messages, it could give you more information about the problem.
  6. Check if the notifySuccess function is being blocked by any security plugin or rules, you can check in your browser’s console to see if there’s any CORS error.
  7. Check if there are any other errors in your code that might be preventing the notifySuccess function from working correctly.
  8. Check if the event listener is correctly attached to the DOM element, and that the function is being called when the event is fired.

These are some general suggestions, the actual cause of the error may vary depending on the specific circumstances. It would be helpful to check the browser’s developer console and see the error message, it will provide more information about the problem.

21, Feb 2023
Error TS2351: This expression is not constructable. (AJV with TypeScript)

The “Error TS2351: This expression is not constructable” error in TypeScript is typically caused when you are trying to use a class that is not meant to be instantiated.

Here are a couple of things you can try to fix this error:

  1. Make sure that the class you are trying to instantiate is not abstract. Abstract classes cannot be instantiated and must be extended by a derived class.
  2. Make sure that the class you are trying to instantiate is not an interface. Interfaces cannot be instantiated and must be implemented by a class.
  3. Make sure that the class you are trying to instantiate is exported correctly. You should be able to import the class and then create an instance of it.
  4. Make sure that the class you are trying to instantiate is not a type alias. Type aliases cannot be instantiated and must be used as a type.
  5. Make sure that the class you are trying to instantiate is not a namespace. Namespaces cannot be instantiated.
  6. Make sure that the class you are trying to instantiate is in the correct scope, if the class is in a module, you may need to import it.
  7. Make sure that you are using the correct syntax to instantiate the class. In TypeScript, classes must be instantiated with the new keyword.
  8. Make sure that the class is being imported from the correct location.
  9. If you’re using a library like AJV, make sure that the class is being imported from the correct module.
  10. Check if there’s any other error in the file or in the project that is blocking the instantiation of the class.

These are some general suggestions, the actual cause of the error may vary depending on the specific circumstances. It would be helpful to check the code around the line where the error is thrown, this will give more information about the problem.

21, Feb 2023
JavaScript on Next.js and React import error “Unable to resolve path to module ‘../utils/makeId’.eslintimport/no-unresolved”

The “Unable to resolve path to module ‘../utils/makeId’.eslintimport/no-unresolved” error in Next.js and React typically occurs when the JavaScript interpreter is unable to find the specified module.

Here are a couple of things you can try to fix this error:

  1. Check the file path of the import statement. Make sure that the file path is correct and that the file exists at the specified location. If the file path is incorrect or the file does not exist, it will result in an import error.
  2. Check if the file is correctly exported. Make sure that the file is exporting the correct component or function. If the file is not exporting anything, or if it is exporting the wrong component or function, it will result in an import error.
  3. Check if the file has been added to the .gitignore file or if there’s any other reason that the file is not been uploaded to the server.
  4. Check if the import statement is inside an if statement or another function, if so, make sure that the function or if statement is being executed before the import statement.
  5. Make sure that the import statement is using the correct file extension. Sometimes, the file might have been imported with the wrong extension, such as .jsx instead of .js, or vice versa.
  6. Check if the file is correctly capitalized, if not, correct the capitalization.
  7. Check if the import statement has been commented out, remove the comment if so.
  8. Check if there’s any other error in the file or in the project that is blocking the import statement from being executed.
  9. Make sure that you have the latest version of eslint and the eslint import plugin

These are some general suggestions, the actual cause of the error may vary depending on the specific circumstances. It might be helpful to check the browser’s developer console and check the network tab, this will provide more information about the request, response and possible error messages.

21, Feb 2023
Which equals operator (== vs ===) should be used in JavaScript comparisons ?
Which equals operator (== vs ===) should be used in JavaScript comparisons?

In JavaScript, the == operator performs type coercion before making a comparison, while the === operator does not. This means that if you use ==, JavaScript will try to convert the operands to the same type before making the comparison.

For example, "5" == 5 will return true, because JavaScript converts the string "5" to the number 5 before making the comparison. However, "5" === 5 will return false, because the operands are not of the same type.

It is generally recommended to use the === operator for comparisons in JavaScript, as it provides a more predictable and consistent behavior. It also helps to avoid unexpected results caused by type coercion.

However, in some cases, using == can be useful, for example when comparing values with different types but that you want to consider equal, like comparing null and undefined.

In summary, use === operator when you want a strict comparison without type coercion, and use == when you want a comparison with type coercion.

21, Feb 2023
How to disable JavaScript build error in Visual Studio 2017?
How to disable JavaScript build error in Visual Studio 2017?

In Visual Studio 2017, you can disable JavaScript build errors by changing the project’s build settings. Here’s how:

  1. Open your project in Visual Studio 2017.
  2. In the Solution Explorer, right-click on the project and select “Properties”.
  3. In the Properties window, navigate to the “TypeScript Build” section.
  4. Uncheck the “Enable TypeScript build” option.

This will disable the TypeScript build for your project, and TypeScript errors will no longer appear in the Error List. However, please keep in mind that disabling the TypeScript build will also disable the TypeScript IntelliSense, syntax checking and other TypeScript related features that can help you during the development process.

Another approach to avoid this issue is to install the JavaScript Language Service, you can do this by going to the “Extensions and Updates” window, searching for “JavaScript Language Service” and installing it. This extension can be a great help with development and debugging, and it can help you to fix the code.

This extension will allow Visual Studio to identify JavaScript as a language, and it will be able to provide IntelliSense, error checking and other features. It’s important to notice that this feature is not installed by default, so you may need to check whether you have it installed or not.

It’s important to note that the error messages displayed during the build can help you to identify and fix issues, so disabling the build may not be the best option. It’s also a good idea to check if there’s a way to address the root cause of the error.