Detailed analysis of JS timer instance

  • 2020-03-26 21:27:00
  • OfStack

1. Counter timer: timename=setTimeout("function();" , delaytime);
2. Loop timer: timename=setInterval("function();" , delaytime);
The first parameter, "function()", is the action to be executed when the timer is triggered. It can be a function or several functions, with "; "between functions. Separate them. For example, to pop up two warning Windows, type "function();" Switch to
"Alert (' first warning window! '); Alert (' second warning window! ');" ; The second parameter "delaytime" is the interval time, in milliseconds, that is, fill in "5000", represents 5 seconds.
The difference between a countdown timer, which triggers events after the specified time has arrived, and a loop timer, which triggers events repeatedly when the interval has arrived, is that the former only works once, while the latter works continuously.
For example, when you open a page and want to automatically jump to another page within a few seconds, you need to use a backtimer "setTimeout("function();"). Delaytime), and if you want to set a sentence to appear one word at a time,
We need to use the loop timer "setInterval("function();" , delaytime) ".

Access to the focus of the form, then use document. ActiveElement. Id. To judge the document using the if. ActiveElement. To the same form of id and id.
Such as: the if (" mid "= = document. ActiveElement. Id) {alert (); },"mid" is the corresponding ID of the form.

Used to specify the execution of a program after a specified period of time.

JS timing execution,setTimeout and setInterval differences, and l unwinding method

SetTimeout (Expression,DelayTime). After DelayTime, an Expression and a setTimeout will be executed for a delay of some time, and then an operation will be performed.
SetTimeout ("function",time) sets a timeout object

SetInterval (expression,delayTime), each delayTime, will execute expression. Often used to refresh expressions.
SetInterval ("function",time) sets a timeout object

SetInterval repeats automatically. SetTimeout does not repeat.

ClearTimeout (object) clears the setTimeout object that has been set
ClearInterval (object) clears the setInterval object that has been set

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