JavaScipt Timing EventsIntroduction
Before explaining the article, I would like to thank all readers who read my article and voted for it. Your appreciation for my article gives me strength to write more good articles. Hope in future I will get your valuable comments and suggestions. Now I won't waste your time and come back to the topic. I have written this article on ‘JavaScript Timing Events’. By using JavaScript, it is possible to execute some code after a specified time-interval.
The two key methods that are used are:
• setTimeout() - executes a code some time in the future
• clearTimeout() - cancels the setTimeout()
Note: The setTimeout() and clearTimeout() are both methods of the HTML DOM Window object.
1. setTimeout () Method
Syntax
var t=setTimeout("javascript statement",milliseconds);
The setTimeout() method returns a value - In the statement above, the value is stored in a variable called t. If you want to cancel this setTimeout(), you can refer to it using the variable name.
The first parameter of setTimeout() is a string that contains a JavaScript statement. This statement could be a statement like "alert ('5 seconds!')" or a call to a function, like "alertMsg()".
The second parameter indicates how many milliseconds from now you want to execute the first parameter.
Note: There are 1000 milliseconds in one second.
Example
When the button is clicked in the example below, an alert box will be displayed after 5 seconds.
Example
2. Example - Infinite Loop
To get a timer to work in an infinite loop, we must write a function that calls itself.
In the example below, when a button is clicked, the input field will start to count (for ever), starting at 0.
Notice that we also have a function that checks if the timer is already running, to avoid creating additional timers, if the button is pressed more than once:
Example
3. The clearTimeout() Method
Syntax
clearTimeout(setTimeout_variable)
Example
The example below is the same as the "Infinite Loop" example above. The only difference is that we have now added a "Stop Count!" button that stops the timer:
Example