Intresting Javascript tricks

var a = 10 , b = 20 ; 
console.log("a = " + a + " , b = " + b);  // a = 10 , b = 20
b = [a, a = b][0];                        // swap the variables 
console.log("a = " + a + " , b = " + b);  // a = 20 , b = 10

function isNumeric (arg) {
    return !isNaN(parseFloat(arg)) && isFinite(arg);
}