Transition Word Checker Check for transition words and phrases to improve text flow.

The tool's core functionality relies on a combination of regular expressions and string manipulation to identify transition words in the input text. It uses the `RegExp` object in JavaScript to create word-boundary regex patterns for each transition word, ensuring that only whole words are matched. The `gi` flag is used to make the matching case-insensitive, allowing it to correctly identify transition words regardless of their case in the input text. The transition words themselves are stored in a `Record<string, string[]>` data structure, which maps each category to an array of corresponding transition words.

When processing the input text, the tool splits it into individual sentences using a regular expression that matches one or more whitespace characters following a period, exclamation mark, or question mark. It then iterates over each sentence, checking for the presence of transition words from the predefined categories. The `match` method is used to find all occurrences of each transition word in the sentence, and the results are stored in an array of objects containing the category, word, and count of each matched transition word.

The tool also uses React's `useCallback` hook to memoize the processing function, ensuring that it is only recreated when the component's dependencies change. This helps to improve performance by reducing unnecessary re-renders of the component. The result is a detailed report on the usage of transition words in the input text, including the total number of sentences, sentences with transitions, and transition density.

The report also includes a breakdown of the transition words found, grouped by category, along with suggestions for using transitions from underrepresented categories to improve the flow of the text. The threshold for determining whether the text has a good use of transition words is set at 30%, based on SEO research. If the percentage of sentences with transitions is above this threshold, the tool indicates that the text has a good use of transition words and flows well. Otherwise, it suggests adding more transitions to improve the flow. The `TextToolLayout` component from the `@/components/shared` module is used to render the input field, output label, and processing results.