JavaScript study notes (15) js intermittent calls and timeout calls_Basic knowledge

1. Call setTimeout() after timeout
The setTimeout() method accepts two parameters, the first parameter is the function, the second parameter is the time (in microseconds), and returns the numerical ID

Copy code The code is as follows:

setTimeout( function () {
alert("Hello!");
},1000);

Cancel clearTimeout() before calling, accept a parameter timeout call ID

Copy code The code is as follows:

var timeOutId = setTimeout( function () {
alert("Hello!");
},1000);

clearTimeout(timeOutId);

2. Intermittently call setInterval()
The setInterval() method accepts two parameters, the first parameter is a function, and the second parameter is time (unit: microseconds ), return the numerical ID

Copy code The code is as follows:

setInterval( function () {
alert("Hello!");
},1000);

Cancel the call to clearInterval(), accept a parameter intermittent call ID

Copy code The code is as follows:

var intervalId = null;
var span = document.createElement("span"); // Create span node
span.Id="time"; //Set span id
document.body.appendChild(span); //Add span in body
function incrementNumber () {
var now = new Date();
var timeStr = now.toLocaleTimeString();
span.innerText =timeStr;
num ;
if (num == 10) {
clearInterval(intervalId ); //The time will remain unchanged after ten seconds
}
}
intervalId = setInterval(incrementNumber,1000);

3. Try to use timeout calls instead of intermittent calls

Copy code The code is as follows:

var num = 0;
var max = 10;
function incrementNumber() {
num ;
if (numsetTimeout(incrementNumber,1000);
} else {
alert("OK");
}
}
setTimeout(incrementNumber,1000);