What's the significant use of unary plus and minus operators?
If unary + / - operators are used to perform conversions as the Number() casting function, then why do we need unary operators? What's the special need of these unary operators?
The Unary + operator converts its operand to Number type. The Unary - operator converts its operand to Number type, and then negates it. (per the ECMAScript spec)
In practice, Unary - is used for simply putting negative numbers in normal expressions, eg:
var x = y * -2.0;
That's the unary minus operator at work. The Unary + is equivalent to the Number() constructor called as a function, as implied by the spec.
I can only speculate on the history, but the unary +/- operators behave similarly in many C-derived languages. I suspect the Number() behavior is the addition to the language here.
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