Question

Here is my javascript code:

var prevDate = new Date('1/25/2011'); // the string contains a date which
                                      // comes from a server-side script
                                      // may/may not be the same as current date

var currDate = new Date();            // this variable contains current date
    currDate.setHours(0, 0, 0, 0);    // the time portion is zeroed-out

console.log(prevDate);                // Tue Jan 25 2011 00:00:00 GMT+0500 (West Asia Standard Time)
console.log(currDate);                // Tue Jan 25 2011 00:00:00 GMT+0500 (West Asia Standard Time)
console.log(prevDate == currDate);    // false -- why oh why

Notice that both dates are the same but comparing using == indicates they are not the same. Why?

Answer 1

I don’t think you can use == to compare dates in JavaScript. This is because they are two different objects, so they are not “object-equal”. JavaScript lets you compare strings and numbers using ==, but all other types are compared as objects.

That is:

var foo = "asdf";
var bar = "asdf";
console.log(foo == bar); //prints true

foo = new Date();
bar = new Date(foo);
console.log(foo == bar); //prints false

foo = bar;
console.log(foo == bar); //prints true

However, you can use the getTime method to get comparable numeric values:

foo = new Date();
bar = new Date(foo);
console.log(foo.getTime() == bar.getTime()); //prints true