Develop Reference

unable to insert a new key value pair to the existing pair

We have name value pair field in our table.These field can be modified i.e either existing values can be changed or a new pair might get added .
We have written the below script to update existing values .
Please help on how to add ,new pair to the existing .
for (var name in u_service_characteristics) {
if (parsed.service_characteristics[name] != null &&
parsed.service_characteristics[name] != undefined) {
u_service_characteristics[name] = parsed.service_characteristics[name];
}
}
Above code only modifies the existing names ,how to insert if the incoming name doesnt exist.

I am guessing this is what you need
var existings = Object.getOwnPropertyNames(u_service_characteristics);
for (var name in parsed.service_characteristics) {
if (!existings.includes(name)) {
u_service_characteristics[name] = parsed.service_characteristics[name];
}
}

Instead of iterating over the keys of the target, just iterate over the keys of the source:
for(var name in parsed.service_characteristics)

Javascript search if LocalStorage variable exists

I am programming a chat system. I always make a Localstorage variable when a new chat is opened. Created like this:
localStorage.setItem("chat_"+varemail, data);
Now i want to check how many of them I have so something like:
"chat_"+... count.
How can I do this?

You'd grab the array of keys of the localStorage object, and use Array.filter to grab only the items starting with "chat_":
var length = Object.keys(localStorage).filter(function(key) {
return /^chat_.+/.test(key);
}).length;
Here's a JSFiddle

Try something like this, loop through all items in localStorage and match against your pattern
function getChatCount(){
var chatCount = 0;
for(item in localStorage){
if(item.indexOf('chat_') > -1) chatCount++;
}
return chatCount;
}

Local storage is based on key, value pairs. AFAIK, you wouldn't be able to retrieve all values with a certain prefix.
One potential solution would be to store an object that contains these. Based on your needs you could store the objects in an array or object and then retrieve the entire set and find the count.
For example:
var chats = { count: 0 };
chats["chat_"+varemail] = data;
chats.count += 1;
localStorage.setItem('chats', data);
Then if you want a count, you would retrieve the object:
var chats = localStorage.getItem('chats');
//chats.count would give you the count.
Although, this would mean you have to manually maintain the count variable when adding or removing data. If you don't need the indexing ability, you could add the chats to an array and store that.
EDIT: It is possible to find properties with a certain prefix, as seen in an answer to this question.

I would offer to convert to localStorage.setItem("chat", JSON.stringify(stack)), where stack is an array of chat objects. This way, you have access to an array of chats which you can count, search within, etc.
Something like:
var chatStore =
{
Count: function () {
var stack = JSON.parse(localStorage.getItem("chats"));
if (!stack)
return 0;
return stack.length;
},
Peek: function () {
var stack = JSON.parse(localStorage.getItem("chats"));
if (!stack)
stack = [];
if (stack.length > 0)
return stack.pop();
},
Push: function (token) {
var stack = JSON.parse(localStorage.getItem("chats"));
if (!stack)
stack = [];
stack.push(token);
localStorage.setItem("chats", JSON.stringify(stack));
},
// more methods to you might wish to implement: search, insert, etc.
}
// usage:
chatStore.Push(chatObject); // sets the last chat
chatStore.Peek(); // gets the last chat

Numerically ordered ID's of data objects in Firebase

I am pretty new to the 'game' and was wondering if it's possible to order newly added data (through a form and inputs) to the Firebase numerically so each new data entry gets the ID (number of the last added data +1).
To make it more clear, underneath you can find a screenshot of how data is currently being added right now. The datapoint 0-7 are existing (JSON imported data) and the ones with the randomly created ID belong to new entries. I would like to have the entries to comply to the numbering inside of my Firebase, because otherwise my D3 bar chart won't be visualised.
var firebaseData = new Firebase("https://assignment5.firebaseio.com");
function funct1(evt)
{
var gameName = $('#nameInput').val();
var medalCount = $('#medalsInput').val();
var bool = $('#boolInput').is(':checked');
firebaseData.push().set({games: gameName, medals: medalCount, summergames: bool});
evt.preventDefault();
}
var submit = document.getElementsByTagName('button')[0];
submit.onclick = funct1;
UPDATE:
function funct1(evt)
{
var gameName = $('#nameInput').val();
var medalCount = $('#medalsInput').val();
var bool = $('#boolInput').is(':checked');
for (var i = 0; i < 10; i++)
{
firebaseData.child('7' + i).set({games: gameName, medals: medalCount, summergames: bool}(i)); };
Problem:

There are two ways to generate ids for your document nodes.
Calling .push() on your reference will generate that unique id.
Calling .set() on your reference will allow you to use your own
id.
Right now you're using .push().set({}), so push will generate an new id and the set will simply set the data.
// These two methods are equivalent
listRef.push().set({user_id: 'wilma', text: 'Hello'});
listRef.push({user_id: 'wilma', text: 'Hello'});
Using .set() without .push() will allow you to control your own id.
Using .push():
When managing lists of data in Firebase, it's important to use unique generated IDs since the data is updating in real time. If integer ids are being used data can be easily overwritten.
Just because you have an unique id, doesn't mean you can't query through your data by your ids. You can loop through a parent reference and get all of the child references as well.
var listRef = new Firebase('https://YOUR-FIREBASE.firebaseio.com/items');
// constructor for item
function Item(id) {
this.id = id;
};
// add the items to firebase
for (var i = 0; i < 10; i++) {
listRef.push(new Item(i));
};
// This will generate the following structure
// - items
// - LGAJlkejagae
// - id: 0
// now we can loop through all of the items
listRef.once('value', function (snapshot) {
snapshot.forEach(function (childSnapshot) {
var name = childSnapshot.name();
var childData = childSnapshot.val();
console.log(name); // unique id
console.log(childData); // actual data
console.log(childData.id); // this is the id you're looking for
});
});
Within the childData variable you can access your data such as the id you want.
Using .set()
If you want to manage your own ids you can use set, but you need to change the child reference as you add items.
for (var i = 0; i < 10; i++) {
// Now this will create an item with the id number
// ex: https://YOUR-FIREBASE.firebaseio.com/items/1
listRef.child('/' + i).set(new Item(i));
};
// The above loop with create the following structure.
// - items
// - 0
// - id: 0
To get the data you can use the same method above to loop through all of the child items in the node.
So which one to use?
Use .push() when you don't want your data to be easily overwritten.
Use .set() when your id is really, really important to you and you don't care about your data being easily overwritten.
EDIT
The problem you're having is that you need to know the total amount of items in the list. This feature is not implemented in Firebase so you'll need to load the data and grab the number of items. I'd recommend doing this when the page loads and caching that count if you really desire to maintain that id structure. This will cause performance issues.
However, if you know what you need to index off of, or don't care to overwrite your index I wouldn't load the data from firebase.
In your case your code would look something like this:
// this variable will store all your data, try to not put it in global scope
var firebaseData = new Firebase('your-firebase-url/data');
var allData = null;
// if you don't need to load the data then just use this variable to increment
var allDataCount = 0;
// be wary since this is an async call, it may not be available for your
// function below. Look into using a deferred instead.
firebaseData.once('value', function(snapshot) {
allData = snapshot.val();
allDataCount = snapshot.numChildren(); // this is the index to increment off of
});
// assuming this is some click event that adds the data it should
function funct1(evt) {
var gameName = $('#nameInput').val();
var medalCount = $('#medalsInput').val();
var bool = $('#boolInput').is(':checked');
firebaseData.child('/' + allDataCount).set({
games: gameName,
medals: medalCount,
summergames: bool
});
allDataCount += 1; // increment since we still don't have the reference
};
For more information about managing lists in Firebase, there's a good article in the Firebase API Docs. https://www.firebase.com/docs/managing-lists.html

chrome.storage.local.get results in "Undefined" when called

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 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 combine 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);
});
}

clearing objects from localstorage

with localstorage i have a load of unspecified items saved with dynamic names using a data namespace like so:
localStorage["myAppName.settings.whatever"] = something.whatever;
//and this:
localStorage["myAppName.data."+dynObj.name] = dynObj.data;
I want to keep the settings but not the data. However I won't ever know what all of the names inside of my data object are so I cannot clear them individually. I need to clear these each time my app is loaded but I must keep the settings so
localstorage.clear() is not an option.
I have tried:
localstorage.removeItem("myAppName.data")
but no dice.
Anyone have any thoughts on how to clear dynamically named portions of localstorage?

You can loop through the keys in the localStorage and target them with a reg exp:
Object.keys(localStorage)
.forEach(function(key){
if (/^(myAppName.data.)/.test(key)) {
localStorage.removeItem(key);
}
});
Here's a similar question: HTML5 Localstorage & jQuery: Delete localstorage keys starting with a certain word

try something like
var i = localStorage.length, key;
while (i--) {
key = localStorage.key(i);
if (key.slice(0, 19) !== "myAppName.settings.") {
localStorage.remove(key);
}
}

Tried something like this?
// Select current settings
var settings = localStorage["myAppName.settings"] || {};
// Clear localStorage
localStorage.clear();
// Add settings to localStorage
localStorage["myAppName.settings"] = settings;

Assuming a this.namespace present (in my case 'session') and the underscore library:
_.each(_.keys(localStorage), function(key) {
if (RegExp("^" + this.namespace + "\\.").test(key)) {
return localStorage.removeItem(key);
}
});
And with CoffeeScript:
_.each _.keys(localStorage), (key) ->
if ///^#{#namespace}\.///.test(key)
localStorage.removeItem(key)