settimeout scope ?

BubikolRamios

02-20-2007, 05:14 PM

mainly interested in how to make "/*1.*/" to work. Thanks for help.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html class = "html">
<head class = "head">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Untitled Document</title>
<script language="javascript" type="text/javascript">
function MyObj()
{
this.doIt = function()
{
/*0.*/ test2('b'); //works
/*1.*/ var t=setTimeout("test2('a')",1000); //does not
/*2.*/ var t=setTimeout("this.test('a')",1000); //does not
/*3.*/ var t=setTimeout("myObj.test('a')",1000); //works
};

this.test = function(param)
{
alert(param);
};

function test2(param)
{
alert(param);
}
}

</script>

</head>
<body style = 'height:100%' onload="myObj = new MyObj();" >
<button value="fdjgsda" onclick="myObj.doIt();"> </button>
</body>
</html>

liorean

02-21-2007, 12:30 PM

setTimeout, if given a string argument, compiles that string into the body of a function in the global scope. However, using a string argument is discouraged, so don't do that.

setTimeout can take a function object as it's first argument instead of a string. This function will be called from the global scope, but because JavaScript has closures, the body of the function will keep the local scope in which it was declared. Thus
/* 1. */var t=setTimeout(function(){test2('a')},1000);
/* 2. alt 1. */var me=this,t=setTimeout(function(){me.test('a')},1000);
/* 2. alt 2. */var t=setTimeout((function(me){return function(){me.test('a')}})(this),1000);

BubikolRamios

02-22-2007, 10:58 PM

Thanks. Solved my problem.