After my previous question , I come up to the following working code that is intended to refresh the DOM periodically by replacing the <div id="test_css_id">...</div>
itself. The behavior of both AJAX requests present in the below code is to reload the same code itself.
<div id="test_css_id">
<a id="link_css_id" href="test_url.html">LINK</a>
<script type="text/javascript">
var refreshTimer;
$('#link_css_id').click(function(event) {
event.preventDefault();
$.ajax({
url: $(this).attr('href'),
type: 'PUT',
success: function(data) {
clearInterval(refreshTimer);
$('#test_css_id').replaceWith(data); // Replaces all code including JavaScript with the response data (note: the response data is exactly the same as the code shown here).
}
});
});
$(document).ready(function() {
function refreshFunction(){
$.ajax({
url: 'test_url.html',
type: 'GET',
success: function(data) {
clearInterval(refreshTimer);
$('#test_css_id').replaceWith(data); // Replaces all code including JavaScript with the response data (note: the response data is exactly the same as the code shown here).
}
});
}
refreshTimer = setInterval(refreshFunction, 1000);
});
</script>
</div>
However, as said by the author of the accepted answer , "there are other ways you can do it [..] one way is to wrap all of that code into a module". I am not expert in JavaScript but I would like to understand and learn it a little more.
How can I wrap all of that code into a module in order to avoid using global variables?
Your current code looks like this:
var refreshTimer; //a global variable
$(...).click(...);
To make refreshTimer not global, you need to put it inside a function:
function main(){
var refresherTimer; //this variable is now local to "main"
$(...).click(...);
}
main();
However, doing it this way won't solve the problem completely. While we did get rid of the global variables, we added a new one - the "main" function itself.
The final trick is to turn the "main" function into an anonymous function and invoke it directly. This is the famous "module pattern":
(function(){
var refreshTimer; //local variable to that anonymous function
$(...).click(...);
}()); //and here we call the function to run the code inside it.
The extra parenthesis around everything are important. If you do just function(){}()
instead of (function(){}())
then you will get a syntax error.
这是 JavaScript中模块模式的不错描述。
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