Javascript 如何正确使用 setInterval 和 clearInterval 在两个不同的函数之间切换？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/10485385/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How do I correctly use setInterval and clearInterval to switch between two different functions?
提问by Ian Campbell
For practice I am trying to display a number that increments from 0 - 9, then decrements from 9 - 0, and infinitely repeats.
The code that I have so far seems to be close, but upon the second iteration the setIntervalcalls of my 2 respective functions countUpand countDownseem to be conflicting with each other, as the numbers displayed are not counting in the intended order... and then the browser crashes.
Here is my code:
为了练习，我试图显示一个从 0 - 9 递增，然后从 9 - 0 递减，并无限重复的数字。
我到目前为止的代码似乎接近，但在第二次迭代中setInterval的我2个各自函数的调用countUp，并countDown似乎彼此发生冲突，因为显示的数字没有在预期的顺序计数......然后浏览器崩溃。
这是我的代码：
<!DOCTYPE html>
<html>
<head>
<title>Algorithm Test</title>
</head>
<body onload = "onloadFunctions();">
<script type = "text/javascript">
function onloadFunctions()
{
countUp();
setInterval(countUp, 200);
}
var count = 0;
function countUp()
{
document.getElementById("here").innerHTML = count;
count++;
if(count == 10)
{
clearInterval(this);
countDown();
setInterval(countDown, 200);
}
}
function countDown()
{
document.getElementById("here").innerHTML = count;
count--;
if(count == 0)
{
clearInterval(this);
countUp();
setInterval(countUp, 200);
}
}
</script>
From 0 - 9, up and down: <div id = "here"></div>
</body>
</html>
回答by xandercoded
You need to capture the return value from setInterval( ... )into a variable as that is the reference to the timer:
您需要将返回值捕获setInterval( ... )到一个变量中，因为它是对计时器的引用：
var interval;
var count = 0;
function onloadFunctions()
{
countUp();
interval = setInterval(countUp, 200);
}
/* ... code ... */
function countUp()
{
document.getElementById("here").innerHTML = count;
count++;
if(count === 10)
{
clearInterval(interval);
countUp();
interval = setInterval(countUp, 200);
}
}
回答by Gerardo Lima
@Claude, you are right, the other solution I proposed was too different from original code. This is another possible solution, using setIntervaland switching functions:
@Claude，你说得对，我提出的另一个解决方案与原始代码差别太大。这是另一种可能的解决方案，使用setInterval和切换功能：
function onloadFunctions() {
var count = 0;
var refId = null;
var target = document.getElementById("aux");
var countUp = function() {
target.innerHTML = count;
count ++;
if(count >= 9) {
window.clearInterval(refId);
refId = window.setInterval(countDown, 500);
}
}
var countDown = function() {
target.innerHTML = count;
count --;
if(count <= 0) {
window.clearInterval(refId);
refId = window.setInterval(countUp, 500);
}
}
refId = window.setInterval(countUp, 500);
}
回答by Rocket Hazmat
clearInterval(this);. You can't do that. You need to save the return value from setInterval.
clearInterval(this);. 你不能那样做。您需要将返回值从setInterval.
var interval;
function onloadFunctions()
{
countUp();
interval = setInterval(countUp, 200);
}
var count = 0;
function countUp()
{
document.getElementById("here").innerHTML = count;
count++;
if(count == 10)
{
clearInterval(interval);
countDown();
interval = setInterval(countDown, 200);
}
}
function countDown()
{
document.getElementById("here").innerHTML = count;
count--;
if(count == 0)
{
clearInterval(interval);
countUp();
interval = setInterval(countUp, 200);
}
}
回答by Fabrizio Calderan
try this:
尝试这个：
...
<body onload = "onloadFunctions();">
<script>
var cup, cdown; // intervals
var count = 0,
here = document.getElementById("here");
function onloadFunctions() {
cup = setInterval(countUp, 200);
}
function countUp() {
here.innerHTML = count;
count++;
if(count === 10) {
clearInterval(cup);
cdown = setInterval(countDown, 200);
}
}
function countDown() {
here.innerHTML = count;
count--;
if(count === 0) {
clearInterval(cdown);
cup = setInterval(countUp, 200);
}
}
</script>
From 0 - 9, up and down: <div id = "here"></div>
</body>
you could also create a single reference to #hereelement. Use always ===instead of ==
您还可以创建对#here元素的单个引用。使用始终===代替==
回答by Gerardo Lima
There are many ways to solve this problem, the following is my suggestion:
解决这个问题的方法有很多，以下是我的建议：
function onloadFunctions() {
var count = 0;
var delta = 1;
var target = document.getElementById("here");
var step = function() {
if(count <= 0) delta = 1;
if(count >= 9) delta = -1;
count += delta;
target.innerHTML = count;
window.setTimeout(step, 500);
}
step ();
}
PS: it's safer to use setTimeoutthan setInteval.
PS：使用setTimeout比setInteval.
回答by Flavio
/** Tools */
const log = require('ololog').configure({
locate: false
})
let count = 0
let interval__UP
let interval__DOWN
function countUp () {
count++
log.green('countUp(): ', count)
if (count == 5) {
clearInterval(interval__UP)
interval__DOWN = setInterval(function () {
countDown()
}, 1000)
}
}
function countDown () {
count--
log.red('countDown(): ', count)
if (count == 0) {
clearInterval(interval__DOWN)
interval__UP = setInterval(function () {
countUp()
}, 3000)
}
}
function start () {
countUp()
log.cyan('start()')
interval__UP = setInterval(function () {
countUp()
}, 2000)
}
start()
