Building Interactive Comparison Tools with Vanilla JS — No Framework Needed

Ever found yourself needing to compare a dozen options side by side — mobile plans, broadband packages, credit cards — and wished there was a simple filtering UI to narrow things down? You do not need React, Vue, or any framework for this. A well-structured vanilla JS comparison tool is fast, portable, and surprisingly straightforward to build. In this tutorial, I will walk you through the core pattern I used to build real comparison tools for Malaysian broadband and mobile plans. You can see them live here: Broadband Comparison Mobile Plan Comparison Let us break down the pattern piece by piece. 1. Start with a Clean Data Structure The foundation of any comparison tool is a flat array of objects. Each object represents one item (a plan, product, or service) with consistent keys. const plans = [ { name : " Unifi 300 " , provider : " Telekom Malaysia " , speed : 300 , // Mbps price : 129 , // MYR/month contract : 24 , // months type : " fiber " }, { name : " Maxis Home Fibre 500 " , pro