Compare Multiple variables in javascript

Question

I need to compare four variables.if any two variables are same i need show an alert. i did like the following way.

var a =1;
var b =2;
var c =3;
var d =4;

if((a==b)||(a==c)||(a==d)||(b==c)||(b==d)||(c==d)){
alert("Value is same, Please change the value");
return false;
}

Is that possible to reduce the expression to one condition instant of checking all the variables separately.Kindly advice ... TnQ in advance.

Answer 1

well, i'll toss this into the ring, albeit it is likely not the right approach to this but it is fun. (note: browser compatibility issues and possibly over-kill is about to precede)

var a = 1,
    b = 2,
    c = 1,
    d = 3;
[a, b, c, d].sort(function(a, b) {
    return a - b;
}).reduce(function(a, b) {
    if (a == b) {
        alert('HERE');
    }
    return b;
});

demo here:
http://jsfiddle.net/rlemon/Eu4qG/

further readings:
Array.reduce
Array.sort