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Flow is A STATIC TYPE CHECKER FOR JAVASCRIPT

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Flow is A STATIC TYPE CHECKER FOR JAVASCRIPT

Flow is A Javascript productivity tool

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function area (r) {
  return Math.PI * r * r
}

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function length (value) {
  return value.length


}

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function length (value) {
  if (value != null) {
     return value.length
  }
  return 0
}

const result = length(null)

// @flow

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Contrived examples?

function length (value) {
  if (value != null) {
     return value.length
  }
  return 0
}

module.exports = length

// @flow

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function length (value: string): number {
  if (value != null) {
     return value.length
  }
  return 0
}

module.exports = length

// @flow

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Benefits of Flow type annotations

• Autocompletion
• Makes code more readable (self-documenting)
• Generate documentation
• Code is more likely to work if it compiles, making you more productive

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Third-party modules (like express)?

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const num: number = 10

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Thank you

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