JavaScript if "x = (a || b || c)"语句不工作

Question

我正在用 javascript 编写一个简单的三 Angular 函数程序，我的 if 和 while 语句无法正常工作，因为它们仅在第一个条件为真时通过，即如果您输入 Sine，它会工作，但如果您输入 Cosine，则不会或切线。

<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 以对其进行测试)

Answer 1

你所有的多重比较都是这样的:

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

需要改成这样:

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

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解释一下，当您执行此操作时 ("Sine"|| "Cosine"|| "Tangent")，计算结果仅为 "Sine" 所以 if (sct == ("Sine"|| "Cosine"|| "Tangent")) 与 if (sct == "Sine") 相同，显然不是你想要什么。

---

这是应用了所有更正后的代码:

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")