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Dev.to
7/19/2026
From a Simple JavaScript Calculator to a Useful Real-World Tool

From a Simple JavaScript Calculator to a Useful Real-World Tool

Short summary

A tutorial on evolving a beginner JavaScript calculator into a real-world tool, using a UAE end-of-service gratuity calculator as the example. It covers input validation, rule-based calculation logic, edge cases, and presenting results with clear breakdowns rather than a single number. The post links to a live implementation at thegratuitycalculator.ae.

  • •Demonstrates turning a basic JS calculator into a production tool using UAE gratuity as example
  • •Covers validation, rule translation, edge cases, and result explanation
  • •Includes working code for the calculation layer with daily wage and cap logic

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