React · Theory

Conditional Classes in React

Theory

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Conditional Classes in React

Same problem, class-list angle. A tiny cx helper: parts.filter(Boolean).join(' ') turns ('tab', on && 'tab-on') into 'tab tab-on' or 'tab'. That’s what clsx does. Use it when you have three flags (disabled, active, error).

Conditional Classes in React — output — "tab tab-on" then "tab". Libraries like clsx do this.

Exam tip

cx / clsx for several flags.

Example

// Conditional classes
function cx(...parts) {
  return parts.filter(Boolean).join(" ");
}

export default function Tab({ on }) {
  return <button className={cx("tab", on && "tab-on")}>Home</button>;
}

Conditional Classes in React — output: "tab tab-on" then "tab". Libraries like clsx do this.

Short notes

DefHelper : filter(Boolean).join.
RuleLib : clsx.
RememberFlags : disabled / active / error.

React · Theory

Conditional Classes in React

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Theory

76/94

Conditional Classes in React

Conditional Classes in React — output — "tab tab-on" then "tab". Libraries like clsx do this.

Exam tip

cx / clsx for several flags.

Example

// Conditional classes
function cx(...parts) {
  return parts.filter(Boolean).join(" ");
}

export default function Tab({ on }) {
  return <button className={cx("tab", on && "tab-on")}>Home</button>;
}

Conditional Classes in React — output: "tab tab-on" then "tab". Libraries like clsx do this.

Short notes

DefHelper : filter(Boolean).join.
RuleLib : clsx.
RememberFlags : disabled / active / error.

Conditional Classes in React

Example

Short notes

Questions

Conditional Classes in React

Example

Short notes

Questions