The setValue, the reset, and the defaultValues are the three APIs that control the form’s values from outside the input elements. The defaultValues is the initial state and the comparison baseline. The setValue is the programmatic update for a single field. The reset is the programmatic update for the whole form. The three are related…
The watch function and the useWatch hook read the same form values, but they subscribe at different scopes. The watch function is called on the useForm return object, and it triggers a re-render at the component that owns the useForm call. The useWatch hook is called inside a child component, and it triggers a re-render…
The formState object is the form’s metadata layer, and the four properties that drive most of the UI feedback are isDirty, isValid, touchedFields, and dirtyFields. They are not independent states that the library computes separately; they are derived from the same internal source—the comparison between the current values and the defaultValues, and the interaction history…
The errors object is the part of the formState that holds the validation failures. It is a nested object that mirrors the shape of the form values: a top-level field’s error is errors.email, a nested field’s error is errors.address.city, and an array field’s error is errors.items[0].name or errors.items.0.name. Each error object has a type property…
React Hook Form’s built-in validation rules are the constraints you pass to the register call or to the Controller component. They run through the library’s own validation engine, not through the browser’s Constraint Validation API, which means the error messages are React state, the errors render inside the component, and the validation runs on the…
Biome’s import organization is not a linter rule and not a formatter option. It is an assist action, and the assist is the third tool in the Biome toolchain alongside the formatter and the linter. The distinction matters because the assist actions always come with a code fix—they are not meant to catch bugs or…
Biome’s rule domains are the technology-specific layer that sits on top of the problem-category groups. A domain is a named collection of rules that applies to a particular framework, library, or environment—React, Next.js, Solid, Vue, the test runners, Playwright, Tailwind, Turborepo, and the project-level analysis. The domain is not the same as the group. The…
The Biome linter runs only the recommended rules by default. This is the first thing to understand about the default configuration: a project that adds Biome and does nothing else gets a curated set of rules that the Biome team considers the baseline for correctness and good practice . The recommended rules emit diagnostics with…
Biome’s linter is organized around rules, and every rule belongs to a group. The group is the taxonomy—the category of the problem the rule detects—and the rule is the specific check. The noDebugger rule is in the suspicious group, because a stray debugger statement is likely an accident. The noUnusedVariables rule is in the correctness…
Biome’s formatter is deliberately opinionated. It follows the Prettier philosophy of exposing only a small set of options, and it resists adding new ones to prevent the style debates that turn into the configuration debates . The options that do exist are split into two layers: the language-agnostic options that live in the top-level formatter…