Detailed explanation of the use of javascript timer events_Basic knowledge

Using timing events in JavaScript is easy, two key methods are:

setTimeout()
Execute code at some time in the future

clearTimeout()
Cancel setTimeout()
setTimeout()
Syntax

Copy code The code is as follows:

var t=setTimeout("javascript statement" , milliseconds)

The setTimeout() method will return a certain value. In the above statement, the value is stored in a variable named t. If you wish to cancel this setTimeout(), you can specify it using this variable name.
The first parameter of setTimeout() is a string containing JavaScript statements. This might be a statement such as "alert('5 seconds!')", or a call to a function such as alertMsg()".

The second parameter indicates how many milliseconds from now the first parameter will be executed.

Tip: 1000 milliseconds equals one second.

When the button in the example below is clicked, a prompt box will pop up after 5 seconds.

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Example - Infinite Loop

To create a timer that runs in an infinite loop, we need to write a function that calls itself. In the example below, the input field starts counting from 0 when the button is clicked.

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clearTimeout()

Syntax

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clearTimeout(setTimeout_variable)

Example

The following example is similar to the infinite loop example above. The only difference is that now we've added a "Stop Count!" button to stop the counter:

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Two other important methods:

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setInterval()
setInterval() - executes a function, over and over again, at specified time intervals

Function Yes: Execute a method in a loop within a specified interval

Syntax:

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window.setInterval("javascript function",milliseconds);

Note: The first parameter must be a function, and the second parameter is the interval between executing the function.

Example:

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Note: In the above example, the execution effect is to alert("hello") every 500ms;

Another clock:

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How to stop, setInterval() method??

Copy code The code is as follows:

window.clearInterval()

Syntax:

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window.clearInterval(intervalVariable)

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The window.clearInterval() method can be written without the window prefix.

To be able to use the clearInterval() method, you must use a global variable when creating the interval method:

myVar=setInterval("javascript function",milliseconds);
Then you will be able to stop the execution by calling the clearInterval() method.

Example:

Copy code The code is as follows:

stop

}