一元加减运算符的重要用途是什么？ [英] What's the significant use of unary plus and minus operators?

问题描述

如果一元 + / - 运算符用于执行转换为 Number（ ）转换函数，那为什么我们需要一元运算符？这些一元运营商的特殊需求是什么？

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?

推荐答案

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数字类型，然后将其否定。
（根据 ECMAScript规范）

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)

实际上，一元 - 用于简单地将负数放在正常表达式中，例如：

In practice, Unary - is used for simply putting negative numbers in normal expressions, e.g.:

var x = y * -2.0;

这是工作中的一元减号运算符。一元 + 等同于作为函数调用的Number（）构造函数，如规范所暗示的那样。

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.

我只能推测历史，但是一元+/-运算符在许多C派生语言中表现相似。我怀疑Number（）行为是这里语言的补充。

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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