multiArgumentSyntax.js

var f1 = function(a,b){
    // do something with a and b
    return a + b;
};
var f2 = function(a){
    // can do something with a here
    return function(b){
        // can do something with a and b here
        return a + b;
    };
};

// calling them f1 and f2
var c = f1(10,5);
var d = f2(10)(5);
// can also do
var f3 = f2(10); 
// f3 is a function that adds 10 
// to anything that is input

var e = f3(5); // add 5 to 10

// they are the same except the syntax changes
assert(c == d && d == e);