Often times developers insist that writing code first is the quickest way to get your product launched. For the most part this is a fallacy. Test Driven Development may result in slower ramp up, but that really means more investment in well designed and well structured code. Carpenters call this “measure twice and cut once.” Many developers go with the “measure, cut, measure, cut, measure, cut, glue, measure, get a new piece of wood” approach. Using a testing framework like Jasmine will reduce the overall costs (time and money) and improve the overall product.
TDD is also a great learning tool for newer developers. It helps encourage code reusability and encourages better design by reducing the reliance on monolithically giant functions/methods.
There’s a great write up I just came across that details several more benefits and explains how it improves the quality of the product while simultaneously reducing the overall time to market.