Equals: a b, please note the double equality sign means the equality test, while a single one a b means an assignment. Greater/less than or equals: a > b, a < b. In JavaScript they are written like this: Greater/less than: a > b, a < b. When you call NaN = false the result is false, same with NaN = true. We know many comparison operators from maths. (thanks for remind to But why the short answer worked? Hovewer even NaN = NaN results with false.Ī Simple way to find out if variable is NaN is an global function isNaN().Īnother is x != x which is only true when x is NaN. You wanted to check if NaN = null which results false. The NaN (Not-a-Number) is a weirdo Global Object in javascript frequently returned when some mathematical operation failed. Just use distance || 0 when you want to be sure you value is a proper number or isNaN() to check it. Look at Mozilla Developer Network about NaN. I wrote this answer to another question on StackOverflow where another checks when NaN = null but then it was marked as duplicate so I don't want to waste my job. This operator tries to compare values irrespective of whether they are of different types. So to conclude, if it is true that a variable != itself, then this variable is exactly of value NaN: function isOfValueNaN(v) The JavaScript not equal or inequality operator () checks whether two values are not equal and returns a boolean value. In the light that NaN is the only JavaScript value that is treated unequal to itself, so we can check for its equality to itself using != var myVar // undefined But what we really want to check is if myVar is exactly of value NaN. It actually makes sense, because "A" is actually not a number. What really happens here is that myVar is implicitly coerced to a number: var myVar = "A" IsNaN(myVar) // true, although "A" is not really of value NaN To check if a variable is of value NaN, we cannot simply use function isNaN(), because isNaN() has the following issue, see below: var myVar = "A" NOTE: Same value and different type gives result 'true'. In this any one should be different either value or type. The symbolic representation of Not equal value or Not equal type is. NaN in JavaScript stands for "Not A Number", although its type is actually number. Not equal value or Not equal type is an comparison operator which is used to check whether the two operands are having not equal value or not equal type.
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