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The Next.js React web application runs separate code on the server and in the browser. By default, the environment variables are only accessible in the server side script. Warning: by exposing environment variables to the browser code you may reveal secrets. Make sure the exposed environment variables do not contain any secrets. If secrets are …
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When the Node.js application runs correctly in the development environment, but throws the following error in higher environments: Error: Cannot find module ‘…’ Make sure the module is not listed in the “devDependencies” section of the package.json and package-lock.json files. If you have installed a package with the –save-dev @types/… option, the package is considered a …
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Download the React Developer Tools for the browser you use from https://react.dev/learn/react-developer-tools
When the parameterized PostgreSQL statement has more elements in the “VALUES” option than the number of columns specified, we get the error message: error: INSERT has more expressions than target columns In the sample code below there are two columns listed, and there are three elements in the “VALUES” option. Solution Remove the extra elements …
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For security reasons we should always use parameterized queries to avoid SQL injections through parameters. The usual format is When a PostgreSQL command runs and a parameter is not used, we get the error message error: could not determine data type of parameter $1 Solution: Remove the unused parameter from the “parameters” array, in this …
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If your Next.js React TypeScript web application uses database calls to display data on the pages, and during build time the database is not available, we need to disable the static page generation, otherwise we get the following error: info Generating static pages…TypeError: Failed to parse URL from ……code: ‘ERR_INVALID_URL’ To disable the static page …
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If your application is in the proof of concept phase, it works and you just want to build it, you can disable the linting process to have a successful build regardless of linting errors.
The ESLint static code analysis tool flags code where we operate on objects which can be undefined. Object is possibly ‘undefined’ The end of the red line shows the extent of the object which can be undefined, as the “children” element is defined as optional in the type definition: To satisfy the linter, we need to …
When you create an array in TypeScript the type of the first element defines the type of all elements of the array. When we reuse an array with new data, the array type has already been defined, so when we assign new values to the same array we get the error message: Type error: Type …
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In a TypeScript application ESLint flags code when we try to assign “null” value to string type variables and attributes. This can be necessary when we want to set the value of a database column to “null”. To make a string type attribute nullable, add ” | null ” to the type definition: