test.js

function main() {
  
  {
    let bb = doSomething1()
    let mm = doSomething2(bb, 'ww')
  }
  
  function doSomething2(var1, var2) {
    console.log('nnw')
  }
  
  function doSomething1() {
    console.log('hh')
  }
}

main()

https://gist.github.com/hbt/3e71146454a2d6388338af1d76394a13#file-test-js-L5
This part is defined first when you're thinking of what function should do

https://gist.github.com/hbt/3e71146454a2d6388338af1d76394a13#file-test-js-L6
Use let inside a block to prevent variables from leaking out and being used accidentally in functions

https://gist.github.com/hbt/3e71146454a2d6388338af1d76394a13#file-test-js-L10
Inline functions are defined below and abstract a specific code block away but remain in the function to prevent unnecessary pollution and one-time use

https://gist.github.com/hbt/3e71146454a2d6388338af1d76394a13#file-test-js-L14
If a function needs to be reused, it can easily be extracted and refactored using IDE tools.