首頁猿問 10%0 結(jié)果為NaN？

10%0 結(jié)果為NaN？

JavaScript

胡說叔叔 2018-12-20 18:14:49

任何數(shù)取余0，為什么結(jié)果為NaN；10 % 0;> NaN感謝各位的解答，我覺得還是有些欠妥當(dāng)。都知道任何數(shù) /0 得到的是 Infinity 無窮大的，雖然 %0的計算過程中也涉及除法運(yùn)算，但是它的結(jié)果卻是NaN 而不是 Infinity；本質(zhì)上是有區(qū)別的，javascript指南中提到：算術(shù)運(yùn)算中使用了不恰當(dāng)?shù)牡牟僮鲾?shù)，導(dǎo)致【運(yùn)算失敗】，該運(yùn)算就會返回 NaN 。然而任何數(shù) /0 返回的是 Infinity，這代表的是運(yùn)算是【成功】的。所以我覺得最終返回的 NaN 還是有某個地方的運(yùn)算是有問題的。比如我們都知道 'a'/10 ,結(jié)果是NaN，因?yàn)橐粋€字符，一個是數(shù)字，報錯是理所當(dāng)然的。但是 10%0 為何報錯為NaN?

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達(dá)令說

TA貢獻(xiàn)1821條經(jīng)驗(yàn) 獲得超6個贊

這種問題你想知道結(jié)果，只能去看ECMAScript 標(biāo)準(zhǔn)，因?yàn)橐粋€取模(余數(shù)）運(yùn)算的定義里，小學(xué)生都知道被除數(shù)需要是非0，對于這種情況如何處理？當(dāng)然是標(biāo)準(zhǔn)說怎么處理，就怎么處理
es7標(biāo)準(zhǔn)

找到關(guān)于 % opeartor的定義

12.7.3.3 Applying the % Operator：

If either operand is NaN, the result is NaN.

The sign of the result equals the sign of the dividend.

If the dividend is an infinity, or the divisor is a zero, or both, the result is NaN.

If the dividend is finite and the divisor is an infinity, the result
equals the dividend.

If the dividend is a zero and the divisor is nonzero and finite, the result is the same as the dividend. In the remaining cases, where neither an infinity, nor a zero, nor NaN is involved, the floating-point remainder r from a dividend n and a divisor d is defined by the mathematical relation r = n - (d × q) where q is an integer that is negative only if n/d is negative and positive only if n/d is positive, and whose magnitude is as large as possible without exceeding the magnitude of the true mathematical quotient of n and d. r is computed and rounded to the nearest representable value using IEEE 754-2008 round to nearest, ties to even mode.

看我加粗的那句話，這就不需要我翻譯了吧。。

反對回復(fù) 2019-01-24