Develop Reference

Javascript object to array, length = 0

I'm building a webshop where users are able to add products for one of more stores in their basket and checkout (like AliExpress).
On the cart overview page, the content of the basket is shown sorted by store. If the same product is added multiple times over different stores, the product is show by every store.
Now, I want to create an order for every store with the products ordered by that store. I'm using Angular to create the list with products ordered/filtered by store.
That data will be sent to my Node.JS server, to loop the contents and create some orders with items.
The problem, I think, is that the data is processed like a 'object' and not an 'array'. I have found a function which converts a object to an array, but the length is still '0'.
How can I process the data so I can loop through the different items?
AngularJS code to sort cart by store
$scope.filterProducts = function(groupName) {
$scope.productList = [];
$http({
method: 'GET',
xhrFields: {withCredentials: true},
url: '/loadCart'
}).then(function successCallback(response){
if (response.data) {
var mapByShop = function(arr, groupName) {
return arr.reduce(function(result, item) {
result[item[groupName]] = result[item[groupName]] || {};
result[item[groupName]][item['productId']] = item;
console.log('GROUPNAME en RESULT', groupName, result);
return result;
}, {});
};
if (response.data.length > 0) {
if (groupName == 'shopName') {
$scope.productList = mapByShop(response.data, groupName);
} else {
$scope.checkoutList = mapByShop(response.data, groupName);
}
}
}
}, function errorCallback(response){
console.log(response);
});
}
The $scope.productList is sent as 'data' in a $http POST function.
Node.JS code to convert an object to an array
function convertObjectToArray(object, cb){
var cartContent = [];
for (var i in object) {
cartContent[i] = object[i];
}
console.log("convertObjectToArray");
return cb(cartContent);
}
Code to process the data (where length is zero)
convertObjectToArray(req.body.cart, function(result){
console.log(isArray(result));
console.log('result', result);
console.log("lenght", result.length);
})
FYI: the isArray function
function isArray(myArray) {
return myArray.constructor.toString().indexOf("Array") > -1;
}

if array order is not important, you should use
cartContent.push(object[i]);
It will update the .length property automaticly

Your problem is that you are adding properties to the array object, and not using the Array API to insert at integer locations in the object. This means the array essentially remains "empty". If you key on an integer when inserting into the array then your code will work better.
The broken bit:
for (var i in object) {
cartContent[i] = object[i];
}
i is a string key here and will not increment the length of the Array unless the value coerces to an integer value (I think).
Something like this might work:
// Untested...
var keys = Object.keys(object);
for (var i = 0; i < keys.length; i++) {
cartContent[i] = object[keys[i]];
}
Or like the other answer suggested, use the push API.
Aside:
If you are in a modern JS engine you can:
Use Object.values, or
Write a couple of utility functions and convert an object to an array using the following
:
var o = iterable({foo:'fooValue', bar: 'barValue'});
console.log([...o]);
The utility functions:
function iterable(o) {
if(o[Symbol.iterator]) {
return o;
}
o[Symbol.iterator] = iter.bind(null, o);
return o;
}
function* iter(o) {
var keys = Object.keys(o);
for (var i=0; i<keys.length; i++) {
yield o[keys[i]];
}
}

JavaScript checking if something is unique in an array

I've been searching around SO and google but I'm not sure how to go about what I'm doing. I'm creating my own little app that uses ajax and Yahoo API to bring back RSS feed information and display it to the page, it brings back title, description, thumbnail and GUID.
The issue at hand is data returned in the array with an image is duplicated so my idea is "I'll check guids and if they aren't unique remove one" but what I've tried isn't working. Any advice is appreciated!
This is how I'm getting my data, converting xml into JSON which will contain properties "title, description, pubdate, thumbnail & guid"
function getData() {
return $.getJSON("giant yahoo api url" + "%22&format=json&callback=?",
function(data) {
}
);
Duplicate handling
handlebars.registerHelper("removeDuplicate", function(results) {
var a = results;
var b = results.guid;
var i = 2;
foreach(b in a) {
if( b.count != 1) {
b--;
}
}
});

To fix the duplicate issue I was having I've written a handlebars helper as I was doing before but with a couple of tweaks it now works as intended and returns only the [0] item if the item is in an array!
handlebars.registerHelper("rssFeed", function(results) {
var a = results;
if(Array.isArray(a)) {
return a[0];
}
else {
return a;
}
});

You can filter like below:
var uniques = [];
results.forEach(function(result)) {
var control = true;
uniques.forEach(function(single) {
if(single.guid == result.guid) control = false;
if(control) uniques.push(result);
})
}

You could use Array.prototype.reduce, quick (sloppy) example:
handlebars.registerHelper("removeDuplicate", function(results) {
return results.reduce(function(arr, item) {
var unique = true;
arr.forEach(function(i) {
if (i.guid === item.guid) unique = false;
});
if (!unique) return arr;
arr.push(item);
return arr;
}, []);
});

ReactJS updating a single object inside a state array

I have a state called this.state.devices which is an array of device objects.
Say I have a function
updateSomething: function (device) {
var devices = this.state.devices;
var index = devices.map(function(d){
return d.id;
}).indexOf(device.id);
if (index !== -1) {
// do some stuff with device
devices[index] = device;
this.setState({devices:devices});
}
}
Problem here is that every time this.updateSomething is called, the entire array is updated, and so the entire DOM gets re-rendered. In my situation, this causes the browser to freeze as I am calling this function pretty every second, and there are many device objects. However, on every call, only one or two of these devices are actually updated.
What are my options?
EDIT
In my exact situation, a device is an object that is defined as follows:
function Device(device) {
this.id = device.id;
// And other properties included
}
So each item in the array of state.devices is a specific instant of this Device, i.e. somewhere I'd have:
addDevice: function (device) {
var newDevice = new Device(device);
this.setState({devices: this.state.devices.push(device)});
}
My updated answer how on to updateSomething, I have:
updateSomething: function (device) {
var devices = this.state.devices;
var index = devices.map(function(d){
return d.id;
}).indexOf(device.id);
if (index !== -1) {
// do some stuff with device
var updatedDevices = update(devices[index], {someField: {$set: device.someField}});
this.setState(updatedDevices);
}
}
Problem now is that I get an error that says cannot read the undefined value of id, and it is coming from the function Device(); it seems that a new new Device() is being called and the device is not passed to it.

You can use the react immutability helpers.
From the docs:
Simple push
var initialArray = [1, 2, 3];
var newArray = update(initialArray, {$push: [4]}); // => [1, 2, 3, 4]
initialArray is still [1, 2, 3].
So for your example you will want to do something like this:
if (index !== -1) {
var deviceWithMods = {}; // do your stuff here
this.setState(update(this.state.devices, {index: {$set: deviceWithMods }}));
}
Depending on how complex your device model is you could just 'modify' the object properties in situ:
if (index !== -1) {
this.setState(update(this.state.devices[index], {name: {$set: 'a new device name' }}));
}

In my opinion with react state, only store things that's really related to "state", such as things turn on, off, but of course there are exceptions.
If I were you I would pull away the array of devices as a variable and set things there, so there is what I might do:
var devices = [];
var MyComponent = React.createClass({
...
updateSomething: function (device) {
var index = devices.map(function(d){
return d.id;
}).indexOf(device.id);
if (index !== -1) {
// do some stuff with device
devices[index] = device;
if(NeedtoRender) {
this.setState({devices:devices});
}
}
}
});

For some reason above answers didn't work for me. After many trials the below did:
if (index !== -1) {
let devices = this.state.devices
let updatedDevice = {//some device}
let updatedDevices = update(devices, {[index]: {$set: updatedDevice}})
this.setState({devices: updatedDevices})
}
And I imported update from immutability-helper based on the note from: https://reactjs.org/docs/update.html

I solve it doing a array splice in object I wish modify, before update component state and push of object modified again.
Like example below:
let urls = this.state.urls;
var index = null;
for (let i=0; i < urls.length; i++){
if (objectUrl._id == urls[i]._id){
index = i;
}
}
if (index !== null){
urls.splice(index, 1);
}
urls.push(objectUrl);
this.setState((state) => {
return {urls: urls}
});

How do I remove all the extra fields that DOJO datastore adds to my fetched items?

When fetching an item from a DOJO datastore, DOJO adds a great deal of extra fields to it. It also changes the way the data is structure.
I know I could manually rebuild ever item to its initial form (this would require me to make updates to both JS code everytime i change my REST object), but there certainly has to be a better way.
Perhaps a store.detach( item ) or something of the sort?

The dojo.data API is being phased out, partly because of the extra fields. You could consider using the new dojo.store API. The store api does not add the extra fields.
I have written a function that does what you are looking to do. It follows. One thing to note, my function converts child objects to the { _reference: 'id' } notation. You may want different behavior.
Util._detachItem = function(item) {
var fnIncludeProperty = function(key) {
return key !== '_0'
&& key !== '_RI'
&& key !== '_RRM'
&& key !== '_S'
&& key !== '__type'
};
var store = item._S;
var fnCreateItemReference = function(itm) {
if (store.isItem(itm)) {
return { _reference: itm.id[0] };
}
return itm;
};
var fnProcessItem = function(itm) {
var newItm = {};
for(var k in itm) {
if(fnIncludeProperty(k)) {
if (dojo.isArray(itm[k])) {
// TODO this could be a problem with arrays with a single item
if (itm[k].length == 1) {
newItm[k] = fnCreateItemReference(itm[k][0]);
} else {
var valArr = [];
dojo.forEach(itm[k], function(arrItm) {
valArr.push(fnCreateItemReference(arrItm));
});
newItm[k] = valArr;
}
} else {
newItm[k] = fnCreateItemReference(itm[k]);
}
}
}
return newItm;
};
return fnProcessItem(item);
};
NOTE: this function is modified from what I originally wrote and I did not test the above code.

Advanced search/queue array collection question

I have a pretty large number of objects "usrSession" I store them in my ArrayCollection usrSessionCollection.
I'M looking for a function that returns the latest userSessions added with a unique userID. So something like this:
1.
search the usrSessionCollection and only return one userSessions per userID.
2.
When it has returned x number of userSessions then deleted them from the usrSessionCollection
I'M stuck - would really love some code that can help me with that.
function ArrayCollection() {
var myArray = new Array;
return {
empty: function () {
myArray.splice(0, myArray.length);
},
add: function (myElement) {
myArray.push(myElement);
}
}
}
function usrSession(userID, cords, color) {
this.UserID = userID;
this.Cords = cords;
this.Color = color;
}
usrSessionCollection = new ArrayCollection();
$.getJSON(dataurl, function (data) {
for (var x = 0; x < data.length; x++) {
usrSessionCollection.add(new usrSession(data[x].usrID.toString(), data[x].usrcords.toString() ,data[x].color.toString());
}
});
Thanks.

The biggest issue is that you have made the array private to the outside world. Only methods through which the array can be interacted with are add and empty. To be able to search the array, you need to either add that functionality in the returned object, or expose the array. Here is a modified ArrayCollection:
function ArrayCollection() {
var myArray = new Array;
return {
empty: function () {
myArray.splice(0, myArray.length);
},
add: function (myElement) {
myArray.push(myElement);
},
getAll: function() {
return myArray;
}
}
}
Now to get the last N unique session objects in usrSessionCollection, traverse the sessions array backwards. Maintain a hash of all userID's seen so far, so if a repeated userID comes along, that can be ignored. Once you've collected N such user sessions or reached the beginning of the array, return all collected sessions.
usrSessionCollection.getLast = function(n) {
var sessions = this.getAll();
var uniqueSessions = [];
var addedUserIDs = {}, session, count, userID;
for(var i = sessions.length - 1; i >= 0, uniqueSessions.length < n; i--) {
session = sessions[i];
userID = session.userID;
if(!addedUserIDs[userID]) {
uniqueSessions.push(session);
addedUserIDs[userID] = true;
}
}
return uniqueSessions;
}
I wouldn't combine the delete step with the traversal step, just to keep things simple. So here's the remove method that removes the given session from the array. Again, it's better to modify the interface returned by ArrayCollection rather than tampering with the sessions array directly.
function ArrayCollection(..) {
return {
..,
remove: function(item) {
for(var i = 0; i < myArray.length; i++) {
if(item == myArray[i]) {
return myArray.splice(i, 1);
}
}
return null;
}
};
}
Example: Get the last 10 unique sessions and delete them:
var sessions = usrSessionCollection.getLast(10);
for(var i = 0; i < sessions.length; i++) {
console.log(sessions[i].UserID); // don't need dummy variable, log directly
usrSessionCollection.remove(sessions[i]);
}
See a working example.

You made your array private, so you can't access the data, except adding a new element or removing them all. You need to make the array public, or provide a public interface to access the data. Like first(), next() or item(index).
Then you can add a search(userID) method to the usrSessionCollection, which uses this interface to go through the elements and search by userID.
UPDATE: this is how I would do it: - See it in action. (click preview)
// user session
function userSession(userID, cords, color) {
this.UserID = userID;
this.Cords = cords;
this.Color = color;
}
// a collection of user sessionions
// a decorated array basically, with
// tons of great methods available
var userSessionCollection = Array;
userSessionCollection.prototype.lastById = function( userID ) {
for ( var i = this.length; i--; ) {
if ( this[i].UserID === userID ) {
return this[i];
}
}
// NOTE: returns undefined by default
// which is good. means: no match
};
// we can have aliases for basic functions
userSessionCollection.prototype.add = Array.prototype.push;
// or make new ones
userSessionCollection.prototype.empty = function() {
return this.splice(0, this.length);
};
//////////////////////////////////////////////////////
// make a new collection
var coll = new userSessionCollection();
// put elements in (push and add are also available)
coll.add ( new userSession(134, [112, 443], "#fffff") );
coll.push( new userSession(23, [32, -32], "#fe233") );
coll.push( new userSession(324, [1, 53], "#ddddd") );
// search by id (custom method)
var search = coll.lastById(134);
if( search ) {
console.log(search.UserID);
} else {
console.log("there is no match");
}
// empty and search again
coll.empty();
search = coll.lastById(134);
if( search ) {
console.log(search.UserID);
} else {
console.log("there is no match");
}