Blog: Working with optional Parameters in Flow.js vs TypeScript

[igeligel]

Proposed Blog Title

``

Title slug*

``

Description

type Fee = {
  vatRate: number
}

type FeeWithFootnote = Fee & {
  footnote?: string
}

const lol = (fee: Fee): FeeWithFootnote => {
  if (fee.vatRate === 0.10) {
  	return {
      ...fee,
      footnote: 'adwdawawd'
    }
  }
  return fee
}

In flow vs typescript:

• https://flow.org/try/#0C4TwDgpgBAYh0F4oG8BQUoDcCGwBKuEAXFAHYCuAtgEYQBOqAvqqqJLPAOoCWwAFjAD2g4KRGIO0AGQp0UAGbDR4gPwkAzsDrdSAcyYsAxoNKaoAG0HmoSABTz4JOBACUTrrwFKxwRAD5ZDG55KHt4ADocfEIbBCQABnCARniXQKgASDoIYHI6UnSMDHCShwgAGjkihW9xEgBybAATAHcm7BaOpvqqqGYMfqhs3PyUEvCy5kYgA
• https://www.typescriptlang.org/play/?ssl=1&ssc=1&pln=17&pc=2#code/C4TwDgpgBAYh0F4oG8BQUoDcCGwBKuEAXFAHYCuAtgEYQBOqAvqqqJLPAOoCWwAFjAD2g4KRGIO0AGQp0UAGbDR4gPwkAzsDrdSAcyYsAxoNKaoAG0HmoSABTz4JOBACUTrrwFKxwRAD5ZDG55KHt4ADocfEIbBCQABnCARniXQKgASDoIYHI6UnSMDHCShwgAGjkihW9xEgBybAATAHcm7BaOpvqqqGYMfqhs3PyFeCYgAhttps://www.typescriptlang.org/play/?ssl=1&ssc=1&pln=17&pc=2#code/C4TwDgpgBAYh0F4oG8BQUoDcCGwBKuEAXFAHYCuAtgEYQBOqAvqqqJLPAOoCWwAFjAD2g4KRGIO0AGQp0UAGbDR4gPwkAzsDrdSAcyYsAxoNKaoAG0HmoSABTz4JOBACUTrrwFKxwRAD5ZDG55KHt4ADocfEIbBCQABnCARniXQKgASDoIYHI6UnSMDHCShwgAGjkihW9xEgBybAATAHcm7BaOpvqqqGYMfqhs3PyFeCYgAhttps://www.typescriptlang.org/play/?ssl=1&ssc=1&pln=17&pc=2#code/C4TwDgpgBAYh0F4oG8BQUoDcCGwBKuEAXFAHYCuAtgEYQBOqAvqqqJLPAOoCWwAFjAD2g4KRGIO0AGQp0UAGbDR4gPwkAzsDrdSAcyYsAxoNKaoAG0HmoSABTz4JOBACUTrrwFKxwRAD5ZDG55KHt4ADocfEIbBCQABnCARniXQKgASDoIYHI6UnSMDHCShwgAGjkihW9xEgBybAATAHcm7BaOpvqqqGYMfqhs3PyFeCYgA