我想在while循环中添加一个delay/sleep:
我是这样试的:
alert('hi');
for(var start = 1; start < 10; start++) {
setTimeout(function () {
alert('hello');
}, 3000);
}
只有第一种情况是正确的:在显示alert('hi')后，它将等待3秒，然后alert('hello')将显示，但随后alert('hello')将不断重复。
我想要的是，在警报('hello')显示3秒后警报('hi')，然后它需要等待3秒的第二次警报('hello')，以此类推。
当前回答
/*
Use Recursive and setTimeout
call below function will run loop loopFunctionNeedCheck until
conditionCheckAfterRunFn = true, if conditionCheckAfterRunFn == false : delay
reRunAfterMs miliseconds and continue loop
tested code, thanks
*/
function functionRepeatUntilConditionTrue(reRunAfterMs, conditionCheckAfterRunFn,
loopFunctionNeedCheck) {
loopFunctionNeedCheck();
var result = conditionCheckAfterRunFn();
//check after run
if (!result) {
setTimeout(function () {
functionRepeatUntilConditionTrue(reRunAfterMs, conditionCheckAfterRunFn, loopFunctionNeedCheck)
}, reRunAfterMs);
}
else console.log("completed, thanks");
//if you need call a function after completed add code call callback in here
}
//passing-parameters-to-a-callback-function
// From Prototype.js
if (!Function.prototype.bind) { // check if native implementation available
Function.prototype.bind = function () {
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function () {
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
}
//test code:
var result = 0;
console.log("---> init result is " + result);
var functionNeedRun = function (step) {
result+=step;
console.log("current result is " + result);
}
var checkResultFunction = function () {
return result==100;
}
//call this function will run loop functionNeedRun and delay 500 miliseconds until result=100
functionRepeatUntilConditionTrue(500, checkResultFunction , functionNeedRun.bind(null, 5));
//result log from console:
/*
---> init result is 0
current result is 5
undefined
current result is 10
current result is 15
current result is 20
current result is 25
current result is 30
current result is 35
current result is 40
current result is 45
current result is 50
current result is 55
current result is 60
current result is 65
current result is 70
current result is 75
current result is 80
current result is 85
current result is 90
current result is 95
current result is 100
completed, thanks
*/
其他回答
我可能会使用setInterval，像这样:
var period = 1000; // ms
var endTime = 10000; // ms
var counter = 0;
var sleepyAlert = setInterval(function(){
alert('Hello');
if(counter === endTime){
clearInterval(sleepyAlert);
}
counter += period;
}, period);
你这样做:
console.log(“嗨”) Let start = 1 setTimeout(函数(){ let interval = setInterval(函数(){ if(start == 10) clearInterval(interval) 开始+ + console.log(“你好”) }, 3000) }, 3000) < script src = " https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js " > < /脚本>
试试这个
var arr = ['A','B','C'];
(function customLoop (arr, i) {
setTimeout(function () {
// Do here what you want to do.......
console.log(arr[i]);
if (--i) {
customLoop(arr, i);
}
}, 2000);
})(arr, arr.length);
结果
A // after 2s
B // after 2s
C // after 2s
下面是我用来循环数组的函数:
function loopOnArrayWithDelay(theArray, delayAmount, i, theFunction, onComplete){
if (i < theArray.length && typeof delayAmount == 'number'){
console.log("i "+i);
theFunction(theArray[i], i);
setTimeout(function(){
loopOnArrayWithDelay(theArray, delayAmount, (i+1), theFunction, onComplete)}, delayAmount);
}else{
onComplete(i);
}
}
你可以这样使用它:
loopOnArrayWithDelay(YourArray, 1000, 0, function(e, i){
//Do something with item
}, function(i){
//Do something once loop has completed
}
据我所知，setTimeout函数是异步调用的。你能做的是将整个循环包装在一个异步函数中，并等待一个包含setTimeout的Promise，如下所示:
var looper = async function () {
for (var start = 1; start < 10; start++) {
await new Promise(function (resolve, reject) {
setTimeout(function () {
console.log("iteration: " + start.toString());
resolve(true);
}, 1000);
});
}
return true;
}
然后像这样调用运行它:
looper().then(function(){
console.log("DONE!")
});
请花些时间好好理解异步编程。
