Output an array where a value is added to the next value of the array. The Last value will be added with the first value.

Example: [45, 4, 9, 16, 25] Converted to: [49, 13, 25, 41, 70]

Map() method must be used.

CodePudding user response：

When using Array.prototype.map() you can use the index parameter and in each iteration
to see if it's the end of the array or not like so:

const arr = [45, 4, 9, 16, 25];

const newArr = arr.map((item, i) => {
  return i !== (arr.length - 1) ? item   arr[i   1] : item   arr[0];
})

console.log(newArr);

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Array.prototype.map()

CodePudding user response：

You can try following:

console.log([45, 4, 9, 16, 25].map((item, index, array) => item   array[(index   1) % array.length]))

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CodePudding user response：

This works fine.

const nums = [45, 4, 9, 16, 25];

const newNums = nums.map((item, index) => {
  if(index < nums.length - 1) {
    return item   nums[ index   1]
  }
    return item   nums[0]
})

console.log(newNums) // [ 49, 13, 25, 41, 70 ]