[removed] How to reverse a number?

Question

Below is my source code to reverse (as in mirror) the given number. I need to reverse the number using reverse method of arrays.

var a = prompt(\"Enter a va         


        

Answer 1

I was recently asked how to solve this problem and this was my initial solution:

---

The desired output: 123 => 321, -15 => -51, 500 => 5

function revInt(num) {
// Use toString() to convert it into a String
// Use the split() method to return a new array: -123 => ['-', '1','2','3']
// Use the reverse() method to reverse the new created array: ['-', '1','2','3'] => ['3','2','1','-'];
// Use the join() method to join all elements of the array into a string
  let val = num.toString().split('').reverse().join('');
    // If the entered number was negative, then that '-' would be the last character in
   //  our newly created String, but we don't want that, instead what we want is
  //  for it to be the first one. So, this was the solution from the top of my head.

// The endsWith() method determines whether a string ends with the characters of a specified string
  if (val.endsWith('-')) {
    val = '-' + val;
      return parseInt(val);
  }
      return parseInt(val);
}

console.log(revInt(-123));

---

A way better solution:

After I gave it some more thought, I came up with the following:

   // Here we're converting the result of the same functions used in the above example to 
// an Integer and multiplying it by the value returned from the Math.sign() function.

// NOTE: The Math.sign() function returns either a positive or negative +/- 1, 
// indicating the sign of a number passed into the argument.   

function reverseInt(n) {
      return parseInt(n.toString().split('').reverse().join('')) * Math.sign(n)
}

console.log(reverseInt(-123));

NOTE: The 2nd solution is much more straightforward, IMHO

Answer 2

Assuming @DominicTobias is correct, you can use this:

console.log( 
    +prompt("Enter a value").split("").reverse().join("") 
)

Answer 3

My solution to reverse a string:

var text = ""
var i = 0
var array = ["1", "2", "3"]
var number = array.length
var arrayFinal = []

for (i = 0; i < array.length; i++) {
    text = array[number - 1]
    arrayFinal.push(text)
    text = ""
    number = number - 1
}

console.log(arrayFinal)

Hopes This Helps!

Answer 4

Or, as a one-liner ( x contains the integer number to be inversed):

revX=x.toFixed(0).split('').reverse().join('')-0;

The number will be separated into its individual digits, reversed and then reassembled again into a string. The -0 then converts it into a number again.