When recruiting a Javascript developer, a deep understanding of Javascript and proficiency in popular frameworks such as React, Angular, or Vue.js are key. The candidate should demonstrate the ability to create effective, scalable and modern frontend applications.

It is important that the candidate has solid experience working with HTML5, CSS3, and ES6+. An understanding of responsive design techniques and experience working with CSS preprocessors such as SASS or LESS is essential to effectively create user interfaces.

A Javascript developer must have experience in integrating frontend with backend API services. The ability to work with RESTful APIs, as well as knowledge of GraphQL, is crucial to building dynamic applications that communicate effectively with the server.

The candidate should demonstrate knowledge of website performance optimisation, including resource management, minimising latency and increasing loading speed. The ability to use tools such as Webpack or Gulp to optimise assets is important.

The ability to unit and integration test is essential. The candidate should be familiar with testing tools such as Jest, Mocha, or Jasmine and be able to effectively detect, diagnose and resolve issues in Javascript code.

As project work often takes place in teams, communication skills and the ability to work in a team are important. A Javascript developer should collaborate effectively with other developers, designers, and project managers.