Embracing coding best practices guarantees our Ext JS projects are efficient, maintainable, and scalable. This involves adhering to established guidelines for clear, optimized code, fostering collaboration, and reducing errors.

Unit testing in Ext JS development entails testing individual components or units of code independently to ensure their correct functionality. This practice aids in early bug detection and resolution, bolstering code quality and diminishing the risk of regressions. Automated tests are crucial, as they validate code behavior across diverse scenarios, thereby elevating the reliability and ease of maintenance of web applications.

Code review practices in Ext JS development encompass meticulously scrutinizing code modifications made by developers to ensure they meet quality benchmarks and align with best practices. This procedure aids in pinpointing potential issues, enhancing code readability, and fostering knowledge dissemination among team members. Through consistent code reviews, teams can detect bugs at an early stage, uphold code uniformity, and stimulate collaboration and learning within the development team.

Code quality metrics evaluate Ext JS code, measuring complexity, readability, and reliability. Examples include cyclomatic complexity and code duplication. By analyzing these metrics, developers identify areas for improvement, prioritize refactoring, and ensure adherence to quality standards, enhancing software robustness and maintainability.