Examples of use of setInterval and setTimeout in js_Basic knowledge

setInterval() definition and usage

The setInterval() method executes a function or expression at a specified period (in milliseconds). This method will loop calling the function until the function is explicitly stopped using clearInterval() or the window is closed. The parameter of the clearInterval() function is the ID value returned by setInterval().

Grammar

setInterval(code,millisec[,"lang"])
code required. A function to be called or a string of code to be executed.
millisec is a must. The time interval, in milliseconds, between periodic executions or calls to code.

Return value

A value that can be passed to Window.clearInterval() to cancel periodic execution of code.

Usage example:

Copy code The code is as follows:

< input type="text" id="clock" size="35" />


Stop interval event

setTimeout() definition and usage

The setTimeout() method is used to call a function or calculated expression after a specified number of milliseconds. The difference between this method and the setInterval() method is that this method is only executed once.

Syntax

setTimeout(code,millisec)
code required. The string of JavaScript code to be executed after the function to be called.
millisec required. The number of milliseconds to wait before executing the code, in milliseconds.

Tips:
(1) Although setTimeout() only executes the code once. But if you need to call it multiple times, in addition to using setInterval(), you can also let the executed code itself call the setTimeout() method again to achieve the purpose of multiple executions.
(2) In addition, the setTimeout() method can also return an ID value to facilitate the use of the clearInterval() method to cancel the use of the setTimeout() method.

Usage example:

Copy code The code is as follows:

< script type="text/javascript">
function timedMsg(){
var t=setTimeout("alert('3 seconds up!')",3000);
}
function timedMsgAways(){
alert('3 seconds up!');
var t=setTimeout("timedMsgAways()",3000);
}

For these two methods, it should be noted that if an action is required to be performed accurately after every fixed time interval, it is best to use setInterval, and if you do not want to cause mutual interference due to continuous calls, especially If each function call requires heavy calculations and long processing time, it is best to use setTimeout.