"this" object

Armel Asselin · Sep 19, 2003

Hello,

I'm working on a Javascript interpreter; when I execute this code I cannot
figure out why the inner "c" function returns the input widget as "this"...
could someone tell ??

<input type=button onclick="
function myobject(a) { function c() { return this; } var prop1=a;
this.youpla = c(); }
var i = new myobject();
alert(i.youpla.innerHTML);
" value="bonjour" />

the docs tells when calling "c( )" whithout "object." before it should pass
null as "this" but I get the widget ?

please help
Armel

Martin Honnen · Sep 19, 2003

Armel said:
Hello,

I'm working on a Javascript interpreter; when I execute this code I cannot
figure out why the inner "c" function returns the input widget as "this"...
could someone tell ??

<input type=button onclick="
function myobject(a) { function c() { return this; } var prop1=a;
this.youpla = c(); }
var i = new myobject();
alert(i.youpla.innerHTML);
" value="bonjour" />

the docs tells when calling "c( )" whithout "object." before it should pass
null as "this" but I get the widget ?

In my view the this object should be the global object which is the
window object, and it is that with Netscape and with Opera. Only IE6/Win
makes the this object the containing <form> object, no idea why. I don't
think it is the <input> widget itself. Why do you think so? Which
browser have you tried?

<html>
<head>
<title>this object</title>
</head>
<body>
<form name="formName">
<input type="button"
name="buttonName"
onclick="function myobject(a) {
function c() {
return this;
}
var prop1=a;
this.youpla = c();
}
var i = new myobject();
alert('i.youpla: ' + i.youpla + '\ni.youpla == i: ' +
(i.youpla == i) + '\ni.youpla == this: ' + (i.youpla == this) +
'\ni.youpla == window: ' + (i.youpla == window) + '\ni.youpla ==
document.formName: ' + (i.youpla == document.formName));"
value="bonjour">
</form>
</body>
</html>

Lasse Reichstein Nielsen · Sep 19, 2003

Armel Asselin said:
I'm working on a Javascript interpreter; when I execute this code I cannot
figure out why the inner "c" function returns the input widget as "this"...
could someone tell ??

Are you sure that is what it does?

<input type=button onclick="
function myobject(a) { function c() { return this; } var prop1=a;
this.youpla = c(); }
var i = new myobject();
alert(i.youpla.innerHTML);
" value="bonjour" />

the docs tells when calling "c( )" whithout "object." before it should pass
null as "this" but I get the widget ?

let's trace through the code.

--- start ---
function myobject(a) { function c() { return this; }
var prop1=a;
this.youpla = c(); }
--- Declaration of local function myobject ---
var i = new myobject();
--- call to myobject with this = new object ---
function c() { return this; }
--- declaration of local function c
var prop1=a;
--- local variable set to something, soon to be forgotten
this.youpla = c(); }
--- call to local function c ---
return this;
--- returns the global object, since function not called as method ---
--- youpla property of new object set to global object ---
--- local variable i set to new object
alert(i.youpla.innerHTML);

this should alert the innerHTML of the global/window object. No such
thing exists, so it should alert "undefined". It does for me in IE 6
and Opera 7.

/L

Armel Asselin · Sep 19, 2003

this should alert the innerHTML of the global/window object. No such

thing exists, so it should alert "undefined". It does for me in IE 6
and Opera 7.

I used IE 5...

Lasse Reichstein Nielsen · Sep 19, 2003

Armel Asselin said:
I used IE 5...

I was testing with just the posted code, so with no form element
around it. If I add the form, IE 6 also reports the innerHTML of
the form.

It is perhaps an artifact of how IE makes the properties of the
form visible to the HTML event handler. It is still weird, and
incorrect according to the ECMAScript standard.

/L

Help me sort out this script	1	Oct 17, 2023
Updating JSON object	1	Aug 12, 2023
This code is not working	8	Dec 9, 2020
Song requests	4	Aug 16, 2023
Only one table shows up with the information	2	Mar 29, 2023
Is there a way to pass this state from component to the fetch?	1	Apr 24, 2023
JavaScript: Object Definition Extension	26	Nov 11, 2011
Issue with textbox script?	0	Sep 5, 2022

"this" object

Armel Asselin

Martin Honnen

Lasse Reichstein Nielsen

Armel Asselin

Lasse Reichstein Nielsen

Ask a Question

Similar Threads

Members online

Forum statistics

Latest Threads