My favorite alternative to JavaScript’s switch statement

The post argues that JavaScript’s switch statement often becomes clumsy as code grows, and that object literals plus first-class functions offer a cleaner alternative. It uses invoice pricing as the example and shows how the pricing rules can be separated from the pricing logic.

Reading notes

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• switch is described as a common but cumbersome construct that tends to grow in size and complexity over time.
• JavaScript’s object literal syntax and first-class functions are presented as cleaner, more extensible alternatives.
• The pricing example starts with a switch that applies different discounts by customer type.
• The same logic is then rewritten with an object literal that stores discount values by customer type.
• A further rewrite uses functions as the values in that object so each customer type can contain its own pricing logic.
• The functional version allows arbitrary code inside each rule, including a condition for Preferred customers that only applies the discount to items up to $100.
• The method that calculates price only needs to choose the right function and does not need to know how pricing works internally.
• The pricing rules can live in separate files, which makes it easy to add a new pricing type by adding a new file and key/function pair.
• The author says this approach improves flexibility and modularity and helps avoid regression risk from centralized logic.