Order of variables declared in JS

[chunzg]

Would be grateful if someone could explain the logic behind arr and reversed printing out the same value? Why is arr already reversed?

function isPalindrome(str) {
  var arr = str.replace(/\W/g, '').split('')
  var reversed = arr.reverse()

  console.log(arr)
  console.log(reversed)
}

[ilenia]

The reverse() method reverses an array in place . The first array element becomes the last, and the last array element becomes the first.

Array.prototype.reverse()

[jsdisco]

In other words, the reverse() method changes the original array.

If you want to keep the original array, you’d have to spread it into a new array before applying reverse to it like so:

var reversed = [...arr].reverse()

[ilenia]

also arr.slice().reverse()

[jsdisco]

Yeah, that’s how the ancients did it