I'm building a chrome extension, and I needed to save some data locally; so I used the Storage API . I got to run the simple example and save the data, but when I integrated it with my application, it couldn't find the data and is giving me "Undefined" result.

Here is my Code:

    function saveResults(newsId, resultsArray) {
//Save the result
        for(var i = 0; i < resultsArray.length; i++) {
            id = newsId.toString() + '-' + i.toString();
            chrome.storage.local.set({ id : resultsArray[i] });
        }
//Read and delete the saved results
        for(var i = 0; i < resultsArray.length; i++) {
            id = newsId.toString() + '-' + i.toString();
            chrome.storage.local.get(id, function(value){
                alert(value.id);
            });
            chrome.storage.local.remove(id);
        }
    }

I'm building a chrome extension, and I needed to save some data locally; so I used the Storage API . I got to run the simple example and save the data, but when I integrated it with my application, it couldn't find the data and is giving me "Undefined" result.

Here is my Code:

    function saveResults(newsId, resultsArray) {
//Save the result
        for(var i = 0; i < resultsArray.length; i++) {
            id = newsId.toString() + '-' + i.toString();
            chrome.storage.local.set({ id : resultsArray[i] });
        }
//Read and delete the saved results
        for(var i = 0; i < resultsArray.length; i++) {
            id = newsId.toString() + '-' + i.toString();
            chrome.storage.local.get(id, function(value){
                alert(value.id);
            });
            chrome.storage.local.remove(id);
        }
    }

• javascript
• google-chrome-extension

• I think it should be just alert(value); and not alert(value.id); – techfoobar Commented May 4, 2013 at 13:21
• For getting: Use value[id] instead of value.id. For setting, see Using a variable key in chrome.storage.local.set – Rob W Commented May 4, 2013 at 13:28
• when I say "alert(value)" it gives me this "object Object" in the alert box. – Ibrahim Awad Commented May 4, 2013 at 13:29
• when using "value[id]" it results in "undefined" also – Ibrahim Awad Commented May 4, 2013 at 13:31
• 2 @IbrahimAwad The chrome.storage API is fully asynchronous. You have to restructure your code to get it to work. – Rob W Commented May 4, 2013 at 14:00

2 Answers 2

I am not certain what type of data you are saving or how much, but it seems to me that there may be more than one newsId and a resultsArray of varying length for each one. Instead of creating keys for each element of resultsArarry have you considered just storing the entire thing as is. An example of this would be:

chrome.storage.local.set({'results':[]});

function saveResults(newsId, resultsArray) {
  // first bine the data into one object
  var result = {'newsId':newsId, 'resultsArray':resultsArray};

  // next we will push each individual results object into an array
  chrome.storage.get('results',function(item){
    item.results.push(result);
    chrome.storage.set({'results':item.results});
  });
}

function getResults(newsId){
  chrome.storage.get('results', function(item){
    item.results.forEach(function(v,i,a){
      if(v.newsId == newsId){
        // here v.resultsArray is the array we stored
        // we can remove any part of it such as
        v.resultsArray.splice(0,1);
        // or
        a.splice(i,1);
        // to remove the whole object, then simply set it again
        chrome.storage.local.set({'results':a});
      }
    });
  });
}

This way you don't need to worry about dynamically naming any fields or keys.

First of All thanks to Rob and BreadFist and all you guys. I found out why my code wasn't working. Storage.Set doesn't accept the key to be an 'integer' and even if you try to convert that key to be a 'string' it won't work too. So I've added a constant character before each key and it worked. Here's my code.

function saveResults(Id, resultsArray) {
    var key = Id.toString();
    key = 'a'.key;
    chrome.storage.local.set({key : resultsArray});
}

function Load(Id) {
    var key = Id.toString();
    key = 'a'.key;
    chrome.storage.local.get(key, function(result){
        console.debug('result: ', result.key);
    });
}