I humbly ask for assistance. I am working on a project where I need to set up a search to find all instances, inside an Object where a particular value equals whatever term the user is searching for. I found the following code:
function getObjects(obj, key, val) {
var objects = [];
for (var i in obj) {
if (!obj.hasOwnProperty(i)) continue;
if (typeof obj[i] == 'object') {
objects = objects.concat(getObjects(obj[i], key, val));
} else if (i == key && obj[key] == val) {
objects.push(obj);
}
}
return objects;
}
here (to make sure proper credit is given),which works great, but I am looking for some help on expanding the functionality of this code to include the ability to search for more than one element at a time, and also, on the return, display other values in the same objects being returned. As an example, the returns, using the above code, are simply [Object]:
What I was hoping to do was to append the [>Object] with another variable value from the Object, perhaps the ID or Description, both of which are part of the returned results. So, the desired results would be something like "Object: ID=b01" or "Object: Desc = This is Maple", something that will allow my users to quickly see which one of the results they need to look at.
Thank you in advance for your assistance!
From your description, I have changed the function to look through a tree like object and be able to pick out the objects that contain all of the supplied key-value pairs. In addition, it allows you to specify that you want to output extra parameters on the objects that match. (like the id and description)
Here is the code and example
http://jsfiddle.net/hjhQz/
Related
I receive a json from an API that I need to parse and modify one property value. Thing is, the nesting structure of the json data I receive are inconsistent and I have no control over it.
This will prohibit me to specify to look under a certain depth like parsedJson.children[0].property since the property I'm looking for could be found on a different nesting level like parsedJson.children[0].children[0].property on the next iteration.
I currently do it like this, and it works
var parsedJson = JSON.parse('{"a":[{"a1":[{"p":0},{"np":1}]}],"b":[{"p":0},{"np":1}],"c":[{"c1":[{"c2":[{"p":0}]},{"np":1}]}]}')
console.log("before modify")
console.log(parsedJson)
modifyProperty(parsedJson,"p",1);
function modifyProperty(obj,prop,val){
for (var key in obj){
if (key == prop){
obj[key] = val;
}
modifyProperty(obj[key],prop,val);
}
}
console.log("after modify")
console.log(parsedJson)
but I'm afraid later on, if I received a json from API that contains a lot more data and far deeper nesting levels that it may affect performance since this would need to recursively check all children nodes one by one.
Is there a better / faster way to this?
You can pass a second parameter to JSON.parse that recursively transforms all desired property values:
var parsedJson = JSON.parse(
'{"a":[{"a1":[{"p":0},{"np":1}]}],"b":[{"p":0},{"np":1}],"c":[{"c1":[{"c2":[{"p":0}]},{"np":1}]}]}',
(key, val) => key === 'p' ? 1 : val
);
console.log(parsedJson);
I try to add elements in a particular way to the following JSON:
var data = [{"name":"google",
"ip":"10.10.10.01",
"markets":[{"name":"spain","county":"6002,6017,6018,6019,6020"},
{"name":"france","county":"6003,6005,6006,6007,6008,6025,6026,6027,6028,6029"},
{"name":"japan","county":"6004,6021,6022,6023,6024"},
{"name":"korea","county":"6000,6013,6014,6015,6016"},
{"name":"vietnam","county":"6001,6009,6010,6011,6012"}]},
{"name":"amazon",
"ip":"10.10.10.02",
"markets":[{"name":"usa","county":"10000,10001,10002,10003,10004,10005"}]},
{"name":"yahoo",
"ip":"10.10.10.03",
"markets":[{"name":"japan","county":"10000"}]}];
I want to add this element to the json:
newData = [{"name":"amazon",
"ip":"10.10.10.02",
"markets":[{"name":"mexico","county":"9000"}]}];
The result might be exactly this:
var data = [{"name":"google",
"ip":"10.10.10.01",
"markets":[{"name":"spain","county":"6002,6017,6018,6019,6020"},
{"name":"france","county":"6003,6005,6006,6007,6008,6025,6026,6027,6028,6029"},
{"name":"japan","county":"6004,6021,6022,6023,6024"},
{"name":"korea","county":"6000,6013,6014,6015,6016"},
{"name":"vietnam","county":"6001,6009,6010,6011,6012"}]},
{"name":"amazon",
"ip":"10.10.10.02",
"markets":[{"name":"usa","county":"10000,10001,10002,10003,10004,10005"},
{"name":"mexico","county":"9000"}]},
{"name":"yahoo",
"ip":"10.10.10.03",
"markets":[{"name":"japan","county":"10000"}]}];
I tried to use :
$.extend(data.markets, newData)
$.extend(true, data, newData); //this works only in the case every element is new.
but nothing works the way I pretend.
Could anyone give me a solution?
Thanks in advance.
You haven't created JSON, you've created a JavaScript literal object.
You could add this particular piece of newdata by
data[1].markets.push({"name":"mexico","county":"9000"})
Because you are dealing with javascript objects, you can write a function to check for the existence of data[n] and push data.
You have an array of objects, where each object is like the following:
var item = {"name":"...",
"ip":"...",
"markets":[ /*some objects here*/];
}
So why not just creating your custom method to insert elements? It could search in the array if an item with the same name and ip exists, and then:
If it does exist: append the markets to the existing item markets attribute (maybe you need to check again if they already exist). UPDATE:The code that #jasonscript added in his answer will do the job: once you have found where to add the market, just add it to the array. Again, maybe you'll have to check if that market was already in the array. Using jQuery it will be: $.extend(true, data[i],newData)
If it doesn't exist: just add the item to the array: $.extend(true, data,newData)
Stealing a little code from another answer:
$.each(data, function(item){
if(item.name == newData[0].name && item.ip == newData[0].ip) {
item.markets.push.apply(item.markets, newData[0].markets);
}
}
This assumes that you know that all the market items in the new object are different to the existing ones - otherwise you'd have to do a nested foreach or something. If you can change the notation of the objects a little you could think about using a dictionary-like object for Markets to make that a little cleaner.
In fact, changing data from an associative array would probably work for that too. Then you could easily check for existence with:
if(data[myNewDataName]){
//add to markets
} else {
data[myNewDataName] = myNewData;
}
In JS localStorage I can use
localStorage.getItem(key);
to get the value of the entry corresponding to the key in the key variable.
How can I get the entry's ID (instead of value) using the key?
Edit: sorry I must have confused people. What I mean by "key" is the numerical key - which is 0, 1, 2, 3 etc depending on how many items have been saved. Then I want to find out the ID it was stored as, eg foo in the below example, from the numerical key.
localStorage.setItem('foo', 'bar');
LocalStorage is implemented as a key-value pair ( see for instance: https://developers.google.com/web-toolkit/doc/latest/DevGuideHtml5Storage ) - so you don't have an id like an unique auto-incremented id in a database table.
However, you can access the elements using an index - to get the index of a key in localStorage, the only way I can find is to loop through each key until you find the one you are searching for, like this:
var findIndexOfKey = function(searchKey) {
for (var i = 0; i < localStorage.length; i++){
var key = localStorage.key(i);
if(key === searchKey)
return i;
}
return -1;
}
And then, to retrieve the key using the index, you can do:
localStorage.key(myIndex);
And to retrieve the value, you can do this:
localStorage.getItem(localStorage.key(myIndex));
... or this ( which would be equivalent to localStorage.getItem("myKey")):
localStorage.getItem(localStorage.key(findIndexOfKey("myKey")));
when setting the item you should give it's ID as a value and than when you call getItem(key) it should give it's ID as a return ex:
localStorage.setItem('foo', 'bar');
localStorage.getItem('foo'); // it should return the bar
take a look for this examples it may help : http://mathiasbynens.be/notes/localstorage-pattern
The answer:
localStorage.key(key);
Sorry, I realise I've got confused between what's actually called the key, which I called the ID, and it's numerical ID which I called the key...
I don't think it is possible. Can't you just make localStorage.setItem(yourkey,value)? I mean
localStorage.setItem(0,value)
localStorage.setItem(1,value)
This may be useful in loops for example.
I have a json object array. I want to search the array and for each object, create a list of 'services' that is a comma-seperated list of all the keys which have a value of "yes".
The list of json objects with the services list is then displayed in html using jquery's each.
Its a large json file so I want to do it as efficiently as possible.
I already have the object's properties being accessed through jQuery's each (ie, obj.name)
-- so I think it should be possible to filter the services listed for each object using
jQuery's filter, and then display the key if the value is yes.
But it seems like a more efficient option would probably be to create a new javascript array, join the services with a value of yes and then add that variable to the html being
appended.
Im not sure which would be faster and so far havent been very successful at either... so any advice and examples would be very helpful.
Here's what the json array looks like:
[
{"name":"name1",
"service1":"y",
"service2":"y",
"service3":"n",
},
{"name":"name2",
"service1":"n",
"service2":"y",
"service3":"n",
},
];
If you just want to filter the array then use grep.
grep - Finds the elements of an array which satisfy a filter function. The original array is not affected.
http://api.jquery.com/jQuery.grep/
First off, delete trailing commas. Internet Explorer gets really, really confused by them. Anyway, I assume you don't want to "search" the array when you say "for each value"; you want to iterate through the array and parse it into a more usable list. The first method I'd suggest is just passing what you want as the array you desire, but if that's not an option, what you're looking for is some variant of this, which should be fairly efficient (jsFiddle example):
var json = [
{"name":"name1", "service1":"y", "service2":"y", "service3":"n"},
{"name":"name2", "service1":"n", "service2":"y", "service3":"n"}
];
var parsed = {};
for (var i = 0, iLen = json.length; i < iLen; i++) {
// Assuming all we need are the name and a list
var name;
var list = [];
for (var key in json[i]) {
var value = json[i][key];
// We need to hold on to the name or any services with value "y"
if (key === "name") {
name = value;
} else if (value === "y") {
list.push(key);
}
}
// Add them to the parsed array however you'd like
// I'm assuming you want to just list them in plain text
parsed[name] = list.join(", ");
}
// List them on the web page
for (var key in parsed) {
document.write(key + ": " + parsed[key] + "<br>");
}
That way you wind up with a display to the visitor of the services available and still keep an array around for further use if necessary.
jQuery.inArray() Search for a specified value within an array and return its index (or -1 if not found).
http://api.jquery.com/jQuery.inArray/
Or
http://api.jquery.com/jQuery.each/
I need to get just the first item (actually, just the first key) off a rather large associative array in JavaScript. Here's how I'm doing it currently (using jQuery):
getKey = function (data) {
var firstKey;
$.each(data, function (key, val) {
firstKey = key;
return false;
});
return firstKey;
};
Just guessing, but I'd say there's got to be a better (read: more efficient) way of doing this. Any suggestions?
UPDATE: Thanks for the insightful answers and comments! I had forgotten my JavaScript 101, wherein the spec says you're not guaranteed a particular order in an associative array. It's interesting, though, that most browsers do implement it that way. I'd prefer not to sort the array before getting that first key, but it may be unavoidable given my use case.
You can avoid having to create a function by referencing the first entry returned from Object.keys():
var firstKey = Object.keys(data)[0];
For the first entry from a sorted key list, simply add a call to the .sort() method:
var firstKey = Object.keys(data).sort()[0];
There isn't really a first or last element in associative arrays (i.e. objects). The only order you can hope to acquire is the order the elements were saved by the parser -- and no guarantees for consistency with that.
But, if you want the first to come up, the classic manner might actually be a bit easier:
function getKey(data) {
for (var prop in data)
return prop;
}
Want to avoid inheritance properties?
function getKey(data) {
for (var prop in data)
if (data.propertyIsEnumerable(prop))
return prop;
}
In addition to Jonathan's solution, we can also extend the default array functionality:
Array.prototype.getKey = function() {
for (var prop in this)
if (this.propertyIsEnumerable(prop))
return prop;
}