This talk will show that programming in functional style will gain you many benefits writing code: Better readability, better re-usability and new ways of building specific solutions by composing from less specific solutions. The annoyances of doing practical Array processing in ES6, underscore.js or Lo-Dash.js are demonstrated. Hey Underscore, You're Doing It Wrong! Instead other toolkit libraries like Ramda.js let you express data processing work more concise by offering the same breadth of list processing functionality. Another topic discussed is using transducers to gain performance for map-filter and to apply Array processing functions to more general collections, even to streams. Furthermore it is shown that Ramda.js nicely integrates Promises in the functional pipeline.