javascript 在 IF 语句中使用数学函数
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Using Math Functions in an IF statement
提问by Craig
Hi I've just started to learn JavaScript. I'm doing the exercises on http://www.codecademy.com/. You can read it below:
嗨，我刚刚开始学习 JavaScript。我正在http://www.codecademy.com/上做练习。你可以在下面阅读：
FizzBuzz is a children's game where you count from 1 to 20. Easy, right?
FizzBuzz 是一款从 1 数到 20 的儿童游戏。很简单，对吧？
Here's the catch: instead of saying numbers divisible by 3, say "Fizz". And instead of saying numbers divisible by 5, say "Buzz". For numbers divisible by both 3 and 5, say "FizzBuzz".
这里有一个问题：不要说可以被 3 整除的数字，而是说“Fizz”。与其说能被 5 整除的数字，不如说“Buzz”。对于可以同时被 3 和 5 整除的数字，请说“FizzBuzz”。
"1, 2, Fizz, 4, Buzz"...and so forth
“1, 2, Fizz, 4, Buzz”……等等
Let's start by using console.log to print out all of the numbers from 1 and 20.
让我们首先使用 console.log 打印出 1 和 20 中的所有数字。
But don't type out the numbers in order—find a more awesome way!
但是不要按顺序输入数字——找到更棒的方法！
I can get the numbers to print using a for loop but now I don't know how to replace the numbers with strings.
我可以使用 for 循环打印数字，但现在我不知道如何用字符串替换数字。
I thought about doing an IF statement like "if i divided by 3 is zero, then print Fizz" but I'm not sure how to do it. See what I've done so far below:
我想过做一个 IF 语句，比如“如果我除以 3 是零，然后打印 Fizz”，但我不知道该怎么做。看看我在下面做了什么：
var i;
for (i = 0; i <=20; i++) {
console.log(i);
}
if (i / 3 = 0) {
console.log("Fizz")
}
Any help would be great.
任何帮助都会很棒。
回答by
You need to test the remainder with the modulus operator.
您需要使用模运算符测试余数。
if (i % 3 === 0) {
The modulus operator returns the remainder after dividing the left operand by the right.
取模运算符返回左操作数除以右操作数后的余数。
12 % 3; // 0
13 % 3; // 1
14 % 3; // 2
15 % 3; // 0
回答by Pointy
Comparisons are done with the ==(or ===) operator, not =. The latter is for assignments of values to variables or object properties.
比较是使用==(or ===) 运算符完成的，而不是=. 后者用于将值分配给变量或对象属性。
To do your ifstatement, then, you'd write this:
为了做你的if陈述，然后，你会写这个：
if (i / 3 === 0) {
// ...
}
I used ===because it's usuallythe right thing; ==has some weird semantics that can be really confusing before you've gotten the hang of JavaScript.
我使用===它是因为它通常是正确的；==有一些奇怪的语义，在您掌握 JavaScript 之前可能会非常令人困惑。
As @kennebec notes in a comment, you may want to think through your logic again. Perhaps you want to check whether the number is divisibleby three. In that case, you'd want to use the modulus operator:
正如@kennebec 在评论中指出的那样，您可能需要再次思考您的逻辑。也许您想检查这个数字是否可以被 3整除。在这种情况下，您需要使用模运算符：
if (i % 3 === 0) {
// i is divisible by 3
}
回答by Kobe Bryan
var i;
for(i=1; i<=20; i++) {
console.log(i);
if(i / 3 === 0) {
console.log("Fizz");
}
else if(i / 5 === 0) {
console.log("Buzz");
}
}
Hope this will help you proceed to your practice in javascript
希望这能帮助您继续练习 javascript
回答by Debonemo
This works:
这有效：
for (i=1; i<21; i++) {
if(i%3 === 0 && i%5 !== 0) {
console.log("Fizz");
}
else if (i%5 === 0 && i%3 !== 0) {
console.log("Buzz");
}
else if (i%5 === 0 && !i%3 === 0) {
console.log("FizzBuzz");
}
else {
console.log(i);
}
}
回答by Letrstotheprez
Actually you're going to want something more like (i % 3 == 0).
实际上，您会想要更像(i % 3 == 0).
I'm not very familiar with JavaScript so it might be a different operator, if that's the case, %means modulus. It returns the remainder of dividing to numbers. So in your case, let's say iis 3. Then i / 3 == 1, but i % 3 == 0. If iwas 6, i / 3 == 2, but i % 3 == 0still.
我对 JavaScript 不是很熟悉，所以它可能是一个不同的运算符，如果是这种情况，则%表示模数。它返回除法的余数。所以在你的情况下，假设i是3。然后i / 3 == 1，但是i % 3 == 0。如果i是6，i / 3 == 2，但i % 3 == 0仍然。
