为什么我的if / else语句不能正常工作？

Question

I am trying to iterate through the arrays in the numbers variable, and if a number can be divided by 3 I'm logging "fizz", if it can be divided by 5 I'm logging "buzz", and if a number can be divided by 3 + 5, or 15, I'm logging "fizzbuzz"

Here is the working code:

var numbers = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20];
for (var i = 1; i <= numbers.length; i++) {  
    if (i % 15 === 0) {
        console.log("FizzBuzz");
    } else if (i % 5 === 0) {
        console.log("Buzz");
    } else if (i % 3 === 0) {
        console.log("Fizz");
    } else {
        console.log(i);
    }
};

Here is my original code, which doesn't log "fizzbuzz"

var numbers = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20];
for (var i = 1; i <= numbers.length; i++) {      
    if (i % 5 === 0) {
        console.log("Buzz");
    } else if (i % 3 === 0) {
        console.log("Fizz");
    } else if (i % 15 === 0) {
        console.log("FizzBuzz");
    } else {
        console.log(i);
    }
};

Why does the (i % 15 === 0) condition need to precede the other two conditions? Shouldn't it not matter?

Answer 1

The number 15 is divisible by both 3 and 5. If you don't test it first, then you'll never get there.

So let's take 30 as an example. If you check 15 first, you'll see that it's divisible by 15. However, if you check either 5 or 3 first, it'll be flagged as being divisible by either of those.

Answer 2

After one of your conditions evaluates as true, you break out of that if-block and don't evaluate following else-if/else statements. If you want the rest of them to evaluate you can make them if statements instead of else-if's.

Answer 3

It's because firstly the computer checks for the first statement and then the others as you use the ELSE IF which means, to check the statement after the first one is false. Use IF for all instead.