JavaScript如果“x =（a || b || c）”声明不起作用 [英] JavaScript if "x = (a || b || c)" statement not working

问题描述

我在javascript中制作了一个简单的三角函数程序，而我的if和while语句不能正常工作，因为只有在第一个条件为真时它们才会通过，即如果你输入Sine它会起作用，但如果你键入Cosine则不行或者Tangent。

I am making a simple trigonometry program in javascript and my if and while statements are not working properly, as they only pass if the first condition is true i.e. if you type in Sine it will work, but not if you type in Cosine or Tangent.

<script language="JavaScript">
var opposite = 1
var adjacent = 1
var hypotenuse = 1
var sct = "SohCahToa"
while (!(sct == ("Sine" || "Cosine" || "Tangent"))) {
    sct = prompt("Sine (unknown adjacent) / Cosine (unkown opposite side) / Tangent (unknown hypotenuse)")
    if (!(sct == ("Sine" || "Cosine" || "Tangent"))) {
        alert("Spelling error, please try again")
    }
}
if (sct == ("Sine" || "Cosine"))
    hypotenuse = prompt("What is the hypotenuse")
if (sct == ("Sine" || "Tangent"))
    opposite = prompt("What is the opposite side")
if (sct == ("Tangent" || "Cosine"))
    adjacent = prompt("What is the adjacent side")

谢谢
（将代码保存为.html进行测试）

Thanks (save the code as a .html to test it)

推荐答案

所有多重比较如下：

if (sct == ("Sine" || "Cosine" || "Tangent"))

nee d改为：

if (sct == "Sine" || sct == "Cosine" || sct == "Tangent")

---

要解释，当你这样做（正弦||余弦||正切），评估为正弦 so if（sct ==（Sine||Cosine||Tangent））与相同if（） sct ==Sine）这显然不是你想要的。

---

To explain, when you do this ("Sine" || "Cosine" || "Tangent"), that evaluates to just "Sine" so if (sct == ("Sine" || "Cosine" || "Tangent")) is the same as if (sct == "Sine") which is obviously not what you want.

这是您的代码应用了所有更正：

Here is your code with all the corrections applied:

var opposite = 1
var adjacent = 1
var hypotenuse = 1
var sct = "SohCahToa"
while (!(sct == "Sine" || "sct == "Cosine" || sct == "Tangent")) {
    sct = prompt("Sine (unknown adjacent) / Cosine (unkown opposite side) / Tangent (unknown hypotenuse)")
    (!(sct == "Sine" || "sct == "Cosine" || sct == "Tangent")) {
        alert("Spelling error, please try again")
    }
}
if (sct == "Sine" || sct == "Cosine")
    hypotenuse = prompt("What is the hypotenuse")
if (sct == "Sine" || sct == "Tangent")
    opposite = prompt("What is the opposite side")
if (sct == "Tangent" || sct == "Cosine")
    adjacent = prompt("What is the adjacent side")

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