Javascript - 将值增加 4。
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Javascript - increment value by 4.
提问by user1562652
I have a problem.
我有个问题。
I need a Javascript function which increase (increment) variable value by 4, and when the variable value is 20, then set value of variable to 0 and again increment it by 4 and so on...
我需要一个 Javascript 函数，它将变量值增加（增加）4，当变量值为 20 时，然后将变量的值设置为 0，然后再次将其增加 4，依此类推...
I think that I need for loop and if condition, but I don't know how to implement this...
我认为我需要 for 循环和 if 条件，但我不知道如何实现这个...
Example
例子
the result must be:
结果必须是：
x = 0; then x = 4, x = 8, x = 12, x = 16, x = 20, x = 0, x= 4 ....
x = 0; 那么 x = 4, x = 8, x = 12, x = 16, x = 20, x = 0, x= 4 ....
Thank you
谢谢
回答by Ted Hopp
You can do this with a nested pair of loops:
你可以用一对嵌套的循环来做到这一点：
while (true) {
for (var x = 0; x <= 20; x += 4) {
// use x
}
}
This will be more efficient than using the mod (%) operator.
这将比使用 mod ( %) 运算符更有效。
EDIT
编辑
From your comments, it sounds like you want to generate the sequence incrementally, rather than in a loop. Here's a function that will return a function that will generate the next element of your sequence each time you call it:
从您的评论来看，您似乎想逐步生成序列，而不是循环生成。这是一个函数，它将返回一个函数，该函数将在您每次调用时生成序列的下一个元素：
function makeSequence() {
var x = 20; // so it wraps to 0 first time
return function() {
if (x == 20) { x = 0 }
else { x += 4 }
return x;
}
}
You could then use it like this (among many ways):
然后你可以像这样使用它（在很多方面）：
var sequence = makeSequence();
// and each time you needed the next element of the sequence:
var x = sequence();
回答by Joseph Marikle
This is easily solved with a combination of addition operators and modulus %.
这可以通过加法运算符和模数的组合轻松解决%。
x = 0;
//loop
x = (x+4)%24;
回答by Codesen
Following will help
以下将有所帮助
function fnAddVal(val) {
if (val >= 20)
return 0;
else
return val+4;
}
回答by ErikE
Simple!
简单的！
x = (x + 4) % 24;
Do you want an infinite loop? What?
你想要无限循环吗？什么？
回答by Next Door Engineer
You can try something like this for your loop:
你可以为你的循环尝试这样的事情：
<html>
<body>
<script language="javascript">
int x = 0;
while ( x <= 20 )
{
alert("The number is " + x)
if ( x >= 20 )
{
x = 0;
}
x += 4;
}
</script>
</body>
</html>
