is 'this' always defined for functions?

Y

yawnmoth

http://www.frostjedi.com/terra/scripts/demo/this.html

'this' is defined, as I understand it, for event handlers, but why is
it defined, here?

Here's the code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" >
<head>
<title>this</title>
</head>

<body>
<script type="text/javascript">
(function() {
if (this) {
alert("test exists");
} else {
alert("test doesn't exist");
}
})();
</script>
</body>
</html>
 
J

Joost Diepenmaat

yawnmoth said:
http://www.frostjedi.com/terra/scripts/demo/this.html

'this' is defined, as I understand it, for event handlers, but why is
it defined, here?

Here's the code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" >
<head>
<title>this</title>
</head>

<body>
<script type="text/javascript">
(function() {
if (this) {
alert("test exists");
} else {
alert("test doesn't exist");
}
})();
</script>
</body>
</html>
Click to expand...

"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object (the "window" object, ignoring some details).

In method calls on a specific object, "this" refers to the object of
the call (and DOM events act like method calls in that respect).

function bla() {
// do something with "this"
}

bla() // act on the global object

var foo = { bar: bla }

foo.bla() // act on the foo object

var zee = {};

foo.bla.call(z) // act on the zee object
 
T

Thomas 'PointedEars' Lahn

Joost said:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Click to expand...

Period. The rest of that paragraph is unnecessary to mention here and
ultimately misleading.


PointedEars
 
J

Joost Diepenmaat

Thomas 'PointedEars' Lahn said:
Joost said:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Click to expand...

Period. The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...

You know, it would have been more informative for anyone following
this thread if you'd quoted the part you objected to, and refered to
the current thread where you're discussing that subject. This kind of
reply is not helping anyone.

Thomas, I respect your knowledge and insight, but I really do not like
your posting style.

For future readers: the window/global object thread starts at
Message-ID: <EK%[email protected]>
 
T

Thomas 'PointedEars' Lahn

Joost said:
Thomas 'PointedEars' Lahn said:
Joost said:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Click to expand...
Period. The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...

You know, it would have been more informative for anyone following
this thread if you'd quoted the part you objected to, and refered to
the current thread where you're discussing that subject. This kind of
reply is not helping anyone.
Click to expand...

It would have helped you, would you not have fallen victim to your
self-delusions.
Thomas, I respect your knowledge and insight, but I really do not like
your posting style.
Click to expand...

Go on crying. I am not going to repeat myself just to pamper those who
cannot seem to follow this simple rule of Usenet: read before you post.


Score adjusted

PointedEars
 
J

Joost Diepenmaat

Thomas 'PointedEars' Lahn said:
Joost said:
Thomas 'PointedEars' Lahn said:
Joost Diepenmaat wrote:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Period. The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...

You know, it would have been more informative for anyone following
this thread if you'd quoted the part you objected to, and refered to
the current thread where you're discussing that subject. This kind of
reply is not helping anyone.
Click to expand...

It would have helped you, would you not have fallen victim to your
self-delusions.
Thomas, I respect your knowledge and insight, but I really do not like
your posting style.
Click to expand...

Go on crying. I am not going to repeat myself just to pamper those who
cannot seem to follow this simple rule of Usenet: read before you post.


Score adjusted
Click to expand...

Please adjust it a lot lower, and don't bother replying to me.
 
T

Thomas 'PointedEars' Lahn

Joost said:
Thomas 'PointedEars' Lahn said:
Joost said:
Joost Diepenmaat wrote:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Period. The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
You know, it would have been more informative for anyone following
this thread if you'd quoted the part you objected to, and refered to
the current thread where you're discussing that subject. This kind of
reply is not helping anyone.
Click to expand...
It would have helped you, would you not have fallen victim to your
self-delusions.
[...]
Score adjusted
Click to expand...

Please adjust it a lot lower, and don't bother replying to me.
Click to expand...

My apologies, this was uncalled for. While I do not think the thread
reference was necessary (we discussed that only hours ago), my quoting
was certainly suboptimal as was my second followup here.


PointedEars
 
Y

yawnmoth

Joost said:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Click to expand...

Period.  The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...

Do they constitute poor coding practices, or something? I actually
thought it was useful (didn't know about call(), for instance),
although if I should be doing something differently, I'd like to
know...
 
J

Joost Diepenmaat

Thomas 'PointedEars' Lahn said:
Joost said:
Thomas 'PointedEars' Lahn said:
Joost Diepenmaat wrote:
Joost Diepenmaat wrote:
You know, it would have been more informative for anyone following
this thread if you'd quoted the part you objected to, and refered to
the current thread where you're discussing that subject. This kind of
reply is not helping anyone.
It would have helped you, would you not have fallen victim to your
self-delusions.
[...]
Score adjusted
Click to expand...

Please adjust it a lot lower, and don't bother replying to me.
Click to expand...

My apologies, this was uncalled for. While I do not think the thread
reference was necessary (we discussed that only hours ago), my quoting
was certainly suboptimal as was my second followup here.
Click to expand...

Apologies accepted.

I'm looking forward to more constructive (if occasionally heated)
discussions in the future.

Joost.
 
T

Thomas 'PointedEars' Lahn

yawnmoth said:
Joost said:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Click to expand...
Period. The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...

Do they constitute poor coding practices, or something?
Click to expand...

Not Joosts examples, they are OK (but see below). (It would turn out my
suboptimal quoting was even more misleading than what I was actually
referring to. Sigh. [psf 10.1])
I actually thought it was useful (didn't know about call(), for
instance), although if I should be doing something differently, I'd like
to know...
Click to expand...

Function.prototype.call() should be feature-tested before called because it
is not universally supported:

<http://PointedEars.de/es-matrix/#f>


HTH

PointedEars
 
J

Joost Diepenmaat

yawnmoth said:
Joost said:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Click to expand...

Period.  The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...

Do they constitute poor coding practices, or something? I actually
thought it was useful (didn't know about call(), for instance),
although if I should be doing something differently, I'd like to
know...
Click to expand...

Thomas has (reasonably justifiable) objections to calling the "window"
object the global object. See the 'Why "window.alert()" over
"alert()"?' thread (I linked to it in this one).
 
Y

yawnmoth

yawnmoth said:
Joost Diepenmaat wrote:
"this" means the object of a method call. in short, whenever it
doens't refer to anything more specific, it refers to the global
object [...]
Period.  The rest of that paragraph is unnecessary to mention here and
ultimately misleading.
Click to expand...
Click to expand...
Do they constitute poor coding practices, or something?
Click to expand...

Not Joosts examples, they are OK (but see below).  (It would turn out my
suboptimal quoting was even more misleading than what I was actually
referring to.  Sigh. [psf 10.1])
I actually thought it was useful (didn't know about call(), for
instance), although if I should be doing something differently, I'd like
to know...
Click to expand...

Function.prototype.call() should be feature-tested before called because it
is not universally supported:

<http://PointedEars.de/es-matrix/#f>
Click to expand...

Thanks! I'll need to read that "Why "window.alert()" over
"alert()"?" thread Joost mentioned :)
 

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