yougovs

// flatten arrays with a recursive function
function flattenArray(array){
  let flattenedArray = []
  for(let element of array) {
    if(Array.isArray(element)) {
      flattenedArray.push(...flattenArray(element))
    }
    else {
      flattenedArray.push(element)
    }
  }
  return flattenedArray
}

// unit testing
let tests = [
  {
    name: "Empty array",
    parameter: [],
    result: [],
  }, {
    name: "Flat array",
    parameter: [1,2,3],
    result:[1,2,3],
  }, {
    name: "Flat array",
    parameter: [1,[2],3],
    result:[1,2,3],
  }, {
    name: "Two levels array",
    parameter: [1,2,3,[[3],2]],
    result:[1,2,3,3,2],
  }, {
    name: "Very nested array",
    parameter: [1,[2,[[3],[[[[]]]]]]],
    result:[1,2,3],
  }
]

for(let test of tests) {
  const result = flattenArray(test.parameter)
  if( compareArrays(result,test.result)) {
    console.log(`${test.name} succeded`)
  }
  else {
    console.log(`${test.name} failed with [${result}], expected [${test.result}]`)
    console.log(result)
    console.log(test.result)
  }
}

// helper function
function compareArrays(array1, array2) {
  for(let i in array1){
    if(array1[i]!==array2[i]) {
      return false
    }
  }
  return true
}