Detailed analysis of JS timer examples_javascript skills

1. Countdown 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 one function or several functions. The functions can be separated by ";". For example, if you want to pop up two warning windows, you can replace "function();" with
"alert('First warning window!'); alert('Second warning window!');"; and The second parameter "delaytime" is the interval time in milliseconds, that is, filling in "5000" means 5 seconds.
The countdown timer triggers an event after the specified time arrives, while the loop timer triggers the event repeatedly when the interval arrives. The difference between the two is that the former only works once, while the latter works continuously.
For example, after you open a page and want to automatically jump to another page every few seconds, you need to use the countdown timer "setTimeout("function();",delaytime)", and if you want to To set a sentence to appear one word at a time,
requires the use of the loop timer "setInterval("function();",delaytime)".

To obtain the focus of the form, document.activeElement.id is used. Use if to determine whether document.activeElement.id and the form's ID are the same.
For example: if ("mid" == document.activeElement.id) {alert();}, "mid" is the ID corresponding to the form.

Timer:
is used to specify a program to be executed after a specific period of time.

Timing execution in JS, the difference between setTimeout and setInterval, and the cancellation method

setTimeout(Expression,DelayTime), after DelayTime, an Expression will be executed. setTimeout is used to delay for a period of time before performing an operation.
setTimeout("function",time) sets a timeout object

setInterval(expression, delayTime), Expression will be executed for each DelayTime. It can often be used to refresh expressions.
setInterval("function", time) sets a timeout object

SetInterval is automatically repeated, and setTimeout will not be repeated.

clearTimeout(object) clears the setTimeout object
clearInterval(object) clears the setInterval object