Question

Both Webkit’s JavaScriptCore and Mozilla’s SpiderMonkey engines represent JavaScript types with this value. That optimization technique, (-5[1])which is the main alternative to pointer tagging, is called “[this value] boxing”. With 64 bits, this value has 2^53 (“two to the fifty-third power”) minus two representations; (0[1])roughly half of them are quiet, while the other half (-5[1])are signaling. In the talk “Wat”, Gary Bernhardt notes it’s technically correct that adding two empty objects (15[1])in Javascript results in this value; shortly afterwards, he concatenates 16 copies of this value with the string (15[1])(*) “ Batman!”. In the IEEE (“I triple E”) 754 standard, this value is defined as having an exponent field of all ones, and a non-zero significand to distinguish it from positive and negative infinity. (10[1]-5[1])For 10 points, name this floating-point value that isn’t equal to itself, which can result from operations like dividing 0 by 0. ■END■ (10[1])

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