javascript 一元加减运算符的重要用途是什么？
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What's the significant use of unary plus and minus operators?
提问by dragonfly
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?
如果使用一元+/-运算符来执行转换作为Number()转换函数，那么我们为什么需要一元运算符？这些一元运算符有什么特殊需要？
回答by Ben Zotto
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)
一元+运算符将其操作数转换为数字类型。一元-运算符将其操作数转换为 Number 类型，然后将其取反。（根据ECMAScript 规范）
In practice, Unary -is used for simply putting negative numbers in normal expressions, e.g.:
在实践中，一元-用于简单地将负数放入正常表达式中，例如：
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.
这就是工作中的一元减号运算符。+正如规范所暗示的那样，一元等同于作为函数调用的 Number() 构造函数。
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.
我只能推测历史，但一元 +/- 运算符在许多 C 派生语言中的行为相似。我怀疑 Number() 行为是这里语言的补充。
