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Executing this snippet in the Chrome console:
function foo() { return typeof null === 'undefined'; } for(var i = 0; i < 1000; i++) console.log(foo());should print 1000 times false, but on some machines will print false for a number of iterations, then true for the rest.
Why is this happening? Is it just a bug?
367
The reasoning behind this is that null , in contrast with undefined , was (and still is) often used where objects appear. In other words, null is often used to signify an empty reference to an object. When Brendan Eich created JavaScript, he followed the same paradigm, and it made sense (arguably) to return "object" .
In JavaScript null is "nothing". It is supposed to be something that doesn't exist. Unfortunately, in JavaScript, the data type of null is an object. You can consider it a bug in JavaScript that typeof null is an object.
The value null represents the intentional absence of any object value. It is one of JavaScript's primitive values and is treated as falsy for boolean operations.
The JavaScript specification says about null : null is a primitive value that represents the intentional absence of any object value. If you see null (either assigned to a variable or returned by a function), then at that place should have been an object, but for some reason, an object wasn't created.
There is a chromium bug open for this:
Issue 604033 - JIT compiler not preserving method behavior
So yes It's just a bug!
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