Array methods

Question 1

findIndex(array, value)

Answer 1

function findIndex(array, value) {
  for (var i = 0; i < array.length; i++) {
    var checkVal = array[i];
    if (checkVal === value) {
      return i;
    }
  }
  return -1;
}

Question 2

getIndexes(array)

Answer 2

function getIndexes(array) {
  var index = [];
  for (var i = 0; i < array.length; i++) {
    index.push(i);
  }
  return index;

}

Question 3

function countdown(number) {

Answer 3

function countdown(number) {
  var arr = [];
  for (var i = number; i >= 1; i--) {
    arr.push(i);

}
return arr;
}

Question 4

Get the tail end of an array

Answer 4

function tail(array) {
  var newArr = [];
  for (var i = 1; i < array.length; i++) {
    var index = array[i];
    console.log(index);
    newArr.push(index);
  }
  return newArr;

}

Question 5

How to distinguish i and array [i]

Answer 5

{name: ‘John’}

Array is an object prototype, so if you’re looking for the property value, like object[key] it will give you ‘John’;
in an array array[i] gives you the value, where as i gives you the property, or index

Question 6

How to omit all falsy values in an array?

Answer 6

if(array[i])

that means if truthy