Javascript Array Sum via for in loop

let theArray = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
let total1 = 0, total2 = 0;

// iterates through the elements of the array using a for... in
// statement to add each element's value to total2
for ( let element in theArray )  
   total2 += theArray[ element ];/*  w  ww  .  j  av  a 2 s . c  om*/

console.log( "Total using for...in: " + total2 );