Square each number in an array in javascript

Question

I\'m trying to square each number in an array and my original code didn\'t work. I looked up another way to do it, but I\'d like to know WHY the original code didn\'t work.<

Answer 1

Best way to Square each number in an array in javascript

Array.prototype.square = function () {
    var arr1 = [];
    this.map(function (obj) {
        arr1.push(obj * obj);
    });
    return arr1;
}
arr = [1, 6, 7, 9];
console.log(arr.square());
arr1 = [4, 6, 3, 2];
console.log(arr1.square())

Answer 2

function squareDigits(num){
  //may the code be with you
  var output = [];
  var splitNum = num.toString();
   for(var i = 0; i < splitNum.length; i++){
     output.push(splitNum.charAt(i))
    }

   function mapOut(){
    var arr = output;
    return arr.map(function(x){
        console.log(Math.pow(x, 2));
    })
   }
   mapOut();
}

squareDigits(9819);

This should work

Answer 3

Math.sqrt gives you square root not square of a number. Use Math.pow with second argument of 2.

Answer 4

Avoid unnecessary loops, use map()function

let array = [1,2,3,4,5];
function square(a){            // function to find square
  return a*a;
}
arrSquare = array.map(square);    //array is the array of numbers and arrSquare will be an array of same length with squares of every number

You can make the code shorter like this:

let array = [1,2,3,4,5];
arrSquare = array.map(function (a){return a*a;});

Answer 5

The original code is taking the square root of the value. The second version is multiplying the value with itself (squaring it). These are inverse operations

Answer 6

function map(square,a) {
  var result = [];
  for(var i=0;i<=a.length-1;i++)
   result[i]=square(a[i]);
  return result;
}

var square = function(x) {
   return x*x;
}

var value=[1,2,3,4];
var final= map(square,value);
console.log(final);

You can also try the above code snippet.