The code copy is as follows:
function foo()
{
}
setInterval( "foo()", 1000);
If you use OO technology, you can do this.
The code copy is as follows:
// constructor
function MyObj
{
function foo()
{
alert( this.data );
}
this.timer = foo;
this.data = "Hello";
setInterval( "this.timer()", 1000 );
}
function Another()
{
// create timer when create object
var obj = new MyObj();
}
However, it doesn't work as you think. The reason is that the function setInterval() does not recognize this variable. A workaround method can do this.
The code copy is as follows:
function Another()
{
var obj = nw MyObj();
setInterval( "obj.timer()", 1000);
}
Obviously, it works correctly, but if you are a perfectionist, you won't be happy with it. Fortunately, this action can be put into the constructor, with a little change in form.
The code copy is as follows:
// constructor
function MyObj
{
function foo()
{
alert( this.data );
}
this.timer = foo;
this.data = "Hello";
var self = this;
setInterval( function() { self.timer(); }, 1000 );
}
function Another()
{
var obj = new MyObj();
}
OK, by using a closure, it's OK. As for the reasons, I want to give readers a thought for themselves.
Finally, give an example of various test cases.
The code copy is as follows:
<html>
<head>
<title>
Hello Timer
</title>
<script language = "JScript">
/*
* There are 3 classes.
*
* 1. timer can run and result is ok
* 2. timer can run and result is wrong
* 3. timer can not run
*
*/
function Obj()
{
function foo()
{
alert( this.timer );
}
this.timer = foo;
//
var me = this;
var f = function() { me.timer(); };
var f2 = function() { this.timer(); };
// 1st class
//setInterval( f, 1000 );
// 3rd class
//setInterval( f2, 1000 );
// 2nd class
//setInterval( me.timer, 1000 );
//setInterval( this.timer, 1000 );
//setInterval( foo, 1000 );
// 3rd class
//setInterval( "this.timer()", 1000);
//setInterval( "me.timer()", 1000);
//setInterval( "foo()", 1000);
}
var o = null;
function OnClick()
{
o = new Obj();
// 1st class
//setInterval( "o.timer()", 1000);
setInterval( function() { o.timer(); }, 1000 );
// 2nd class
//setInterval( o.timer, 1000 );
}
</script>
</head>
<body>
<input type = "button" onclick = "OnClick()" value = "Click me"></input>
</body>
</html>