Is empty string treated as falsy in javascript?

Question

I\'ve noticed that if you have a statement as the following:

var test = \"\" || null

test will evaluate to null b

Answer 1

One dangerous issue of falsey values you have to be aware of is when checking the presence of a certain property.

Suppose you want to test for the availability of a new property; when this property can actually have a value of 0 or "", you can't simply check for its availability using

 if (!someObject.someProperty)
    /* incorrectly assume that someProperty is unavailable */
In this case, you must check for it being really present or not:

if (typeof someObject.someProperty == "undefined")
    /* now it's really not available */

SEE HERE