Square-bracket values let any CSS value be written inline, which is what makes adoption possible and what makes a codebase unmaintainable if it becomes the norm. The moment…
A trace is large and is only interesting when something went wrong, so recording on retry and uploading on failure is the arrangement that stays affordable. if: failure()…
A leading underscore is a convention that anything can ignore; a hash-prefixed field is a syntax error to access from outside. The #field in obj brand check is…
A generated id from a counter or a random value differs between the server render and the client hydration, which is a mismatch React now reports. The colons…
18 mounts, unmounts and remounts every component once in development under StrictMode, so an effect without cleanup runs twice and shows it. Every failure it produces is a…
First Input Delay measures the delay before the first interaction is processed and says nothing about how long the processing took. The attribution data naming the element is…
ref makes an object deeply reactive, which walks the whole structure — expensive and pointless when the object is only ever replaced. The mutation not triggering is the…