Help with JSON iteration

Question

I'm trying to retrieve some data from a JSON response, but this doesn't seem to work:

My javascript code:

 function recommend(response){
 var recommendedList = eval('(' + response.responseText + ')');
 $H(recommendedList).each(function(item){
 alert(item.artist);
 }); 
 }

What I want is to retrieve each artist values from the JSON response.

and the JSON response is of the format:

[
 {"artist":"artist1","location":{"lat":"50.952226","lng":"5.34832","ID":28}},
 {"artist":"artist2","location":{"lat":"52.362287","lng":"4.883965","ID":32}},
 ...
]

A little help would be great. Thanks!

• Mike DeSimone: $H()... is that Prototype? BTW, do not use eval() like that, it's a gaping security hole and source of bugs.
• Mike DeSimone: Also, I think $H() expects an object as input, not a list.

Answer 1

I'm not sure what your $H() function is supposed to be doing (and its existence makes me very sad), but this framework-agnostic snippet seems to get the job done:

for (var index = 0; index < recommendedList.length; index++) {
 alert(recommendedList[index].artist);
} 

Here is a working example: http://jsfiddle.net/VgPy5/

Also, I'm sure you're going to be chastised for using eval() like that. You might consider using JSON.parse() instead.

• Pointy: The "$H()" thing is almost certainly from the Prototype framework.
• Bruno Morgado: Thanks for the JSON.parse() tip.

Answer 2

Guessing from the "$H()" that you're using prototype, I'd just get rid of that "$H()" because the array should already be iterable.

recommendedList.each(function(item) {
 alert(item.artist);
});

Answer 3

Avoid framework features when you need simple things.

for(i=0; i<recommendedList.length; i++) { 
 alert(recommendedList[i].artist);
}

Answer 4

http://www.prototypejs.org/api/hash/each

Pairs are passed as the first argument of the iterator, in the form of objects with two properties:

key, which is the key name as a String

value, which is the corresponding value (and can, possibly, be undefined)

So your item is actually the key. Instead, iterate like:

$H(recommendedList).each(function(key, item){
 alert(item.artist);
 }); 

• pimvdb: @Pointy: I'm not sure but I was trying to point out what was happening. Your solution is preferable indeed.