var a = 2154; //First number  
var b = 458;  //Second number   
var gcd;  
while (a!=b)  
{  
    if (a>b)  
    {  
        a = a -b;  
    }  
    else  
    {  
        b = b - a;  
    }  
}  
gcd = a;  
console.log(gcd);  