Two string - Structured code, using prototype, simulated class function etc., two sliding pointers, make me laugh

Twostring5.js

function processData(input) {
    //Enter your code here
    //split input into arrays
    var inArr = input.split('\n');
    
    inArr.splice(0,1);
    for(var i=0; i<inArr.length; i=i+2){
        var st = new strObj(inArr[i], inArr[i+1]);
        st.isCommon();
        
    }
} 

function strObj(str1, str2)
{
this.str1=str1;
this.str2=str2;
}
strObj.prototype.isCommon = function() { 
    console.log(getCommons(this.str1, this.str2));
} 

function getCommons(s1, s2){
    var a = s1.split('');
    var b = s2.split('');
    a.sort();
    b.sort();
    while( a.length > 0 && b.length > 0 )
  {  
     if      (a[0] < b[0] ){ a.shift(); }
     else if (a[0] > b[0] ){ b.shift(); }
     else /* they're equal */
     {
       return 'YES';
     }
  }
    return 'NO';
}
process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});