Return value if criteria is not met in javascript .some() function -

given array of numbers, wish use javascript's .some() method find first pair of mirror image numbers , return pair.

e.g. [454,86,57,75,16,88]) should return [57,75]. if there no numbers mirror each other, want return [-1,-1]. managed point if there mirror image numbers, numbers returned. however, can't return [-1,-1]. did go wrong?

var a=0 var b=0 arr=[13,15,19,32,49,61,73]  arr.some((x,i)=>{     a=arr[i]     b=arr[i+1]     b= switchit(b)      if(a!==b){     //what if there no mirror image numbers found?        = -1        b = -1     }else{        return a==b     }       })  function switchit(n){     n= n.tostring()     n= n.split("")     var [x,y,z]=[n[0],n[1],n[2]]     n= [z,y,x]     n= n.join("")     n= parseint(n)   return n }   console.log([a,switchit(b)]) 

one simple ajust , code work expected:

arr.some((x,i)=>{     var end = >= (arr.length - 1);     a=arr[i]     if (!end) {         b=arr[i+1]         b = switchit(b)     }     if(a!==b || end){ //note or end variable here        = -1        b = -1     }else{        return a==b     }       }) 

the ajust consists in test when function find end of array