This is in IE 6...
I'm trying to inherit from built-in JS objects - Array, specifically.
However, I'm having some difficulties. I can add array elements to
the child object, and when I retrieve them, they're the same as what I
added. The problem is, the 'length' property remains zero no matter
how many elements the child contains:
<pair.js>
function pair_getValue()
{
return this.value;
}
function Pair( key, value )
{
this.key = key;
this.value = value;
}
Pair.prototype. getValue = pair_getValue;
<end of pair.js>
<map.js>
function map_add( key, value )
{
if( null != this.findKey( key )) return false;
this[ this.getSize() ] = new Pair( key, value );
// this.getSize() will return 0 - ignore for now!
return true;
}
function map_findKey( key )
{
// returns array index of key or null if not found
}
function map_getSize()
{
return this.length;
}
function map_getValue( key )
{
var i = this.findKey( key );
if( null == i ) return null;
return this[ i ].getValue();
}
function Map
{
}
Map.prototype = new Array();
Map.prototype.a dd = map_add;
Map.prototype.f indKey = map_findKey;
Map.prototype.g etSize = map_getSize;
Map.prototype.g etValue = map_getValue;
<end of map.js>
<example>
var test = new Map();
test.add( 'some unique key', 'some value' );
test.getValue( 'some unique key' ); // Returns 'some value'
test.getSize(); // Returns 0 (zero)?!?
<end of example>
I also tried setting the 'this.length' property explicitly. The value
persists in the function where it was set, but returns to zero
afterwards. Does this have anything to do with it being native code?
The point of this map is to make using cookies easier (the full Map
object can parse strings) by making the contents atomic. This means
another object: Cookie. This inherits from Map. This brings another
problem: both objects have 'serialize' functions. Map concatenates
the key/value pairs using a given separator and the equals character.
Cookie then appends the 'expires', 'path', 'domain' and 'secure'
fields (if set) to the Map values. So far, I've used this structure:
function cookie_serializ e()
{
var temp;
// *************** *************** ************
temp = this.base.proto type.serialize( );
// *************** *************** ************
if( this.domain ) temp = temp + ';DOMAIN=' + this.domain;
// Date.toGMTStrin g() was depreciated in v1.3
// and just calls Date.toUDTStrin g()
if( this.expires ) temp = temp + ';EXPIRES=' +
this.expires.to UDTString();
if( this.path ) temp = temp + ';PATH=' + this.path;
if( this.secure ) temp = temp + ';SECURE';
return temp;
}
function Cookie()
{
this.base = Map;
// Set property defaults...
}
Cookie.prototyp e = new Map();
Cookie.prototyp e.serialize = cookie_serializ e();
It works: Map.serialize (map_serialize) is called, but is it correct?
Why doesn't this.base.seria lize() work?
Thanks in advance,
Mike
--
Michael Winter
M.Winter@[no-spam]blueyonder.co.u k (remove [no-spam] to reply)
I'm trying to inherit from built-in JS objects - Array, specifically.
However, I'm having some difficulties. I can add array elements to
the child object, and when I retrieve them, they're the same as what I
added. The problem is, the 'length' property remains zero no matter
how many elements the child contains:
<pair.js>
function pair_getValue()
{
return this.value;
}
function Pair( key, value )
{
this.key = key;
this.value = value;
}
Pair.prototype. getValue = pair_getValue;
<end of pair.js>
<map.js>
function map_add( key, value )
{
if( null != this.findKey( key )) return false;
this[ this.getSize() ] = new Pair( key, value );
// this.getSize() will return 0 - ignore for now!
return true;
}
function map_findKey( key )
{
// returns array index of key or null if not found
}
function map_getSize()
{
return this.length;
}
function map_getValue( key )
{
var i = this.findKey( key );
if( null == i ) return null;
return this[ i ].getValue();
}
function Map
{
}
Map.prototype = new Array();
Map.prototype.a dd = map_add;
Map.prototype.f indKey = map_findKey;
Map.prototype.g etSize = map_getSize;
Map.prototype.g etValue = map_getValue;
<end of map.js>
<example>
var test = new Map();
test.add( 'some unique key', 'some value' );
test.getValue( 'some unique key' ); // Returns 'some value'
test.getSize(); // Returns 0 (zero)?!?
<end of example>
I also tried setting the 'this.length' property explicitly. The value
persists in the function where it was set, but returns to zero
afterwards. Does this have anything to do with it being native code?
The point of this map is to make using cookies easier (the full Map
object can parse strings) by making the contents atomic. This means
another object: Cookie. This inherits from Map. This brings another
problem: both objects have 'serialize' functions. Map concatenates
the key/value pairs using a given separator and the equals character.
Cookie then appends the 'expires', 'path', 'domain' and 'secure'
fields (if set) to the Map values. So far, I've used this structure:
function cookie_serializ e()
{
var temp;
// *************** *************** ************
temp = this.base.proto type.serialize( );
// *************** *************** ************
if( this.domain ) temp = temp + ';DOMAIN=' + this.domain;
// Date.toGMTStrin g() was depreciated in v1.3
// and just calls Date.toUDTStrin g()
if( this.expires ) temp = temp + ';EXPIRES=' +
this.expires.to UDTString();
if( this.path ) temp = temp + ';PATH=' + this.path;
if( this.secure ) temp = temp + ';SECURE';
return temp;
}
function Cookie()
{
this.base = Map;
// Set property defaults...
}
Cookie.prototyp e = new Map();
Cookie.prototyp e.serialize = cookie_serializ e();
It works: Map.serialize (map_serialize) is called, but is it correct?
Why doesn't this.base.seria lize() work?
Thanks in advance,
Mike
--
Michael Winter
M.Winter@[no-spam]blueyonder.co.u k (remove [no-spam] to reply)
Comment