JQuery, setTimeout not working
JavascriptJquerySettimeoutJavascript Problem Overview
I'm still new to JQuery, on the way to getting my ajax example to work i got stalled with setTimeout. I have broken it down to to where it should add "." to the div every second.
The relevant code is in two files.
index.html
<html><head>
<script type='text/javascript' src='jquery.js'></script>
<script type='text/javascript' src='myCode.js'></script>
</head>
<body>
<div id='board'>Text</div>
</body>
</html>
and myCode.js
(function(){
$(document).ready(function() {update();});
function update() {
$("#board").append(".");
setTimeout('update()', 1000); }
})();
the myCode.js file works alright and "update()" runs the first time through but never again.
Javascript Solutions
Solution 1 - Javascript
You've got a couple of issues here.
Firstly, you're defining your code within an anonymous function. This construct:
(function() {
...
)();
does two things. It defines an anonymous function and calls it. There are scope reasons to do this but I'm not sure it's what you actually want.
You're passing in a code block to setTimeout(). The problem is that update() is not within scope when executed like that. It however if you pass in a function pointer instead so this works:
(function() {
$(document).ready(function() {update();});
function update() {
$("#board").append(".");
setTimeout(update, 1000); }
}
)();
because the function pointer update is within scope of that block.
But like I said, there is no need for the anonymous function so you can rewrite it like this:
$(document).ready(function() {update();});
function update() {
$("#board").append(".");
setTimeout(update, 1000); }
}
or
$(document).ready(function() {update();});
function update() {
$("#board").append(".");
setTimeout('update()', 1000); }
}
and both of these work. The second works because the update() within the code block is within scope now.
I also prefer the $(function() { ... } shortened block form and rather than calling setTimeout() within update() you can just use setInterval() instead:
$(function() {
setInterval(update, 1000);
});
function update() {
$("#board").append(".");
}
Hope that clears that up.
Solution 2 - Javascript
setInterval(function() {
$('#board').append('.');
}, 1000);
You can use clearInterval if you wanted to stop it at one point.
Solution 3 - Javascript
SetTimeout is used to make your set of code to execute after a specified time period so for your requirements its better to use setInterval because that will call your function every time at a specified time interval.
Solution 4 - Javascript
This accomplishes the same thing but is much simpler:
$(document).ready(function() {
$("#board").delay(1000).append(".");
});
You can chain a delay before almost any jQuery method.