JavaScript

What is the difference between == and === ?

The 3 equal signs mean "equality without type coercion". Using the triple equals, the values must be equal in type as well. 

== is equal to 

=== is exactly equal to (value and type)

0==false // true 

0===false // false, because they are of a different type

1=="1" // true, auto type coercion

1==="1" // false, because they are of a different type

How do I format a number to a dollar amount in JavaScript?

function formatDollar(num) {

    var p = num.toFixed(2).split(".");

    return "$" + p[0].split("").reverse().reduce(function(acc, num, i, orig) {

        return  num + (i && !(i % 3) ? "," : "") + acc;

    }, "") + "." + p[1];

}

formatDollar(45664544.23423) // "$45,664,544.23"

formatDollar(45) // "$45.00"

formatDollar(123) // "$123.00"

formatDollar(7824) // "$7,824.00"

formatDollar(1) // "$1.00"