comparing two hashes

[Jeff Thies]

I need to check if two hashes are identical.

My thoughts are something like this:

function compareHash(hash1,hash2){

if(hash1.length != hash2.length){return false}

for(var key in hash1){
if(hash1[key] != hash2[key]) return false;
}
return true;
}

Have I missed something, or is there a more direct approach?

Jeff

[Lasse Reichstein Nielsen]

"Jeff Thies" <no****@nospam.net> writes:

I need to check if two hashes are identical.
What is a hash?

My guess is that it is an array that you use to store values in. You
use it as a hash *table* (and you should just use a plain object, not
an array).
My thoughts are something like this:

function compareHash(hash1,hash2){

if(hash1.length != hash2.length){return false}
Not really interesting if you have an array. Not interesting at all if
you don't.
for(var key in hash1){
if(hash1[key] != hash2[key]) return false;
You should compare with !== instead. Otherwise this comparison of two
clearly different objects gives true:
compareHash({key:0},{key:false})
Have I missed something, or is there a more direct approach?

Use objects for hash tables, drop the length comparison, and use !==.

/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

[Jeff Thies]

> > I need to check if two hashes are identical.

What is a hash?
I don't know what it's called in javascript

var hash={'item1': 'value1' , 'item2': 'value2'}

or

var HASH =new Array();

HASH['some_key']='some_value';
My guess is that it is an array that you use to store values in. You
use it as a hash *table* (and you should just use a plain object, not
an array).
Good advice. What I'm trying to do is save this to a temp cookie.

something like:

var hash={'item1' :value1','item2': 'value2'}

document.cookie="my_cookie=[" + escape(hash) + "],["+ escape(hash2) + ..;

I won't always no what the "keys" are so it seemed a good idea to send
them along.

My thoughts are something like this:

function compareHash(hash1,hash2){

if(hash1.length != hash2.length){return false}
Not really interesting if you have an array. Not interesting at all if
you don't.

for(var key in hash1){
if(hash1[key] != hash2[key]) return false;

You should compare with !== instead.

an object comparison? Didn't know that! Seems like hash1[key] is a variable
that could be compared that way.
Otherwise this comparison of two
clearly different objects gives true:
compareHash({key:0},{key:false})
Duh! slaps head.

Have I missed something, or is there a more direct approach?

Use objects for hash tables, drop the length comparison, and use !==.

Will do.

Thanks,
Jeff
/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html> 'Faith without judgement merely degrades the spirit divine.'