Hello, today I am writing again and in this post, I am going to introduce you to how we incur a frequently common code smell called "Side Effects," which occurs when a function modifies an external state beyond its scope.

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Cause

Side effects arise when a function alters variables outside its scope, leading to unexpected behaviors and complicating code comprehension.

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Example

let total = 0

function addToTotal(value: number): void {
  total += value
  console.log(`Total is now: ${total}`)
}

addToTotal(5)

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Solution

An effective solution is to avoid side effects by using pure functions that do not modify external states. Instead of changing global variables, the function should return a new state.

function addToTotal(currentTotal: number, value: number): number {
  const newTotal = currentTotal + value
  console.log(`Total is now: ${newTotal}`)
  return newTotal
}

let currentTotal = 0
currentTotal = addToTotal(currentTotal, 5)

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Benefits

• Improves Readability: By eliminating side effects, the code becomes clearer and more understandable, making it easier for developers to grasp the execution flow without unexpected surprises.

• Facilitates Maintenance: Side-effect-free functions are easier to maintain as their behavior is confined to their scope, avoiding potential conflicts with other parts of the program.

• Reduces Unexpected Errors: By avoiding external modifications, the likelihood of subtle errors arising from unexpected changes in variable states is minimized.

• Promotes Predictability: Functions without side effects yield consistent results, promoting code predictability and facilitating unit testing.

• Enhances Scalability: Code that avoids side effects is more modular and adaptable, easing scalability as the system grows and evolves.

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Thanks for reading me 😊