JavaScript timer example analysis_javascript skills

1. What is a JavaScript timer?

In JavaScript, we can execute code after a set time interval instead of executing it immediately after the function is called.

2. Timer type

One-shot timer: Fires only once after the specified delay time.
Interval trigger timer: trigger once every certain time interval

3. Timer method

1): One-time timer

A):setTimeout(): Execute the code after the specified delay time, and execute it once

Syntax: setTimeout(code, delay time);

Parameter description:

1. The function to be called or the code string to be executed.
2. Delay time: the time to wait before executing the code, in milliseconds (1s=1000ms).

B):clearTimeout():Cancel setTimeout() setting

Syntax: clearTimeout(timer)

Parameter description:
timer: ID value returned by setTimeout(). This value identifies the deferred execution code block to be canceled.

Call setTimeout() and clearTimeout() delay methods:

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A):setInterval(): During execution, execute the code at specified intervals after loading the page
Syntax: setInterval(code, interaction time);

Parameter description:

1. Code: The function to be called or the code string to be executed.

2. Interaction time: The time interval between periodic execution or calling of expressions, measured in milliseconds (1s=1000ms).

Return value:

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

Call function format (assuming there is a clock() function):

setInterval("clock()",1000) or setInterval(clock,1000)

B): The clearInterval() method can cancel the interaction time set by setInterval()

Syntax: clearInterval(timer)

Parameter description:

timer: ID value returned by setInterval().

Call setInterval() and clearInterval() to execute the interval execution method instance

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