The following is used to build up a object array:
var users = {};
var user = {};
user[socket.id] = data.username;
if(users[data.roomname]){
// Room already exists - check user already exists
// if data.username does not value exist is users then:
users[data.roomname].push(user);
}
else{
// New room
users[data.roomname] = [user];
}
Over a few iterations we get something like this:
console.log ( 'Users: ', users );
users { RoomABC:
[ { YidwzgUHPHEGkQIPAAAD: 'Mr Chipps' },
{ 'JG-gtBMyPm0C1Hi1AAAF': 'Mr T' },
{ '2JFGMEdPbgjTgLGVAAAH': 'Mr Chipps' }, ] }
The issue is trying to ensure that each username is unique, so Mr Chipps should not be added again if that name already exists.
The examples I have seen Assume the keys are known. I have tried a number of things including some, indexOf but I am not able to get a simple 'does UserX already exist' to work.
The following is the latest block of code I tried to only add the user if not already present in the obj array. This works, but it seems very clunky to me; nested loops to get at the correct level to check the value and set a counter if a match found, then check the counter to decide if a match was found or not:
if(users[data.roomname]){
// Room already exists - check user already exists
let found = 0;
// Nested loop - seems a little clunky but it works
Object.keys(users[data.roomname]).forEach(key => {
Object.keys(users[data.roomname][key]).forEach(key2 => {
if ( users[data.roomname][key][key2] === data.username ) {
found++;
}
});
});
if ( found == 0 ) {
users[data.roomname].push(user);
}
}
I keep thinking surely there is neat one-liner that can do this check for the existence but I cant get any to work.
You could check the values instead of using the keys and exit early if a name is found
if (users[data.roomname]) {
if (!Object.values(users[data.roomname]).some(v => Object.values(v).some(n => n === data.username))) {
users[data.roomname].push(user);
}
}
Related
So here is my current code for a currency system. This code works to add the new user information in. Obviously this will keep adding the people that are already in it.
if (!currency[message.author.id]) {
currency.push({id: message.author.id, coins: 0});
}
if I change it to this one, nothing happens. It seems there's something wrong with this comparison and I'm not sure what it is considering it worked for other things I have used.
if (!currency[0].id == message.author.id) {
currency.push({id: message.author.id, coins: 0});
}
This looks right to me as it's getting the id property of the first element and checking if they're the same. When I run the code it just doesn't do anything. No errors and nothing in the json file I'm using to store it. It does this when the array is empty and does it when I have an id property in there.
Is this not possible? I don't like having to set it up using the first way because I'd like to be able to access everyone's currency if needed to add or take away without having to do it one person at a time.
I think it should be !==:
if (currency[0].id !== message.author.id) {
currency.push({id: message.author.id, coins: 0});
}
or should be wrapped in brackets:
if (!(currency[0].id == message.author.id)) {
currency.push({id: message.author.id, coins: 0});
}
It sounds like you probably want a data structure that's an object, not an array, so that you can have arbitrary key-value pairs - have the key be the message.author.id.
const currency = {};
// ...
const { id } = message.author;
if (!currency[id]) {
currency[id] = { id, coins: 0 };
} else {
// this author was already inserted - do something else here, if desired
// current[id].coins += coinChangeAmount; // for example
}
Your original code sounds like it's misusing an array as an object, and the currency[0].id == message.author.id will only check the [0]th element of the array, rather than iterating over all possible elements and looking for an ID match.
I am struggling with doing an array search that includes a piece of text that must include back slashes in it. I have tried includes(''); negating includes(''); and also trying similar using indexOf('').
I have a simple array, with at maximum four values; typically it has two, here is how it typically looks:
{tks: Array(2)}
tks: Array(2)
0: "https://mycoolwebsite.net/arcgis/rest/services"
1: "https://mycoolwebsite.com/arcgis/rest/services"
length: 2
__proto__: Array(0)
__proto__: Object
Here are the simple checks I'm trying to do: My second check with *includes* 'wdt' text seems to be working so I assume it's something with the backslashes. Anyway I can handle this? I'm perplexed why my if and else both get hit with the first check below using back slashes... I added the negating on the else to double check.. with and without that in the else, else is always hit.
// right before doing the search I am building the array, just to add more context
for (let i = 0; i < coolObj.length; i++) {
if (coolObj[i].url){
tr = coolObj[i].url;
tks.push(tr);
console.log({tks});
}
}
console.log({tks}); // consoles as I have included above ^
if (tks.includes('/arcgis/rest/services')) {
console.log({tks});
} else if (!tks.includes('/arcgis/rest/services')) {
console.log({tks});
console.log('does not include correct url');
aT = '/arcgis/rest/services';
lP = false;
filterAt(aT);
}
if (tks.includes('wdt')) {
console.log({tks});
}else {
console.log({tks});
wT = 'wdt';
filterWt(wT);
}
From the MDN docs: The includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.
You have to test the strings using String.prototype.includes within the array elements thus:
const arr = ["https://mycoolwebsite.net/arcgis/rest/services", "https://mycoolwebsite.com/arcgis/rest/services"];
arr.forEach(el => {
if (el.includes('/arcgis/rest/services')) {
console.log(el, ': includes url');
}
else {
console.log('does not include correct url');
}
if (el.includes('wdt')) {
console.log(el, ': includes wdt');
} else {
console.log('does not include correct wdt');
}
});
Guys I want to get an element from array. Here:
Follower:
{ follower:
[ 5edfe8f3bfc9d677005d55ca,
5edfe92fbfc9d677005d55cc,
5ee2326cc7351c5bb0b75f1a ],
user id:
5edfe92fbfc9d677005d55cc
The process:
if(follower == user){
console.log("sdasdsad")
}else{
console.log("no")
}
But when I do it it always returns as no.
Also this is the codes of===> Nodejs Follow System Not Working Properly
It is a nodejs project. So please look at the above link.
When I do
if(follower.includes(user)){
It gives the error of:
TypeError: Cannot read property 'includes' of null
And when I try to change some I get this error:
TypeError: takip.includes is not a function
Guys so thats why I say please look at the above code.
So how to equalize them?
As other peoples said earlier the follower itself is a property which its value is an array itself, so if you want to check whether an item exists within it or not you can check it with includes(), if it exists it will return true otherwise it will return false.
const follow = {
follower: ["5edfe8f3bfc9d677005d55ca",
"5edfe92fbfc9d677005d55cc",
"5ee2326cc7351c5bb0b75f1a"
]
}
const user = "5edfe92fbfc9d677005d55cc";
if (follow.follower.includes(user)) {
console.log("sdasdsad")
} else {
console.log("no")
}
But if you looking to find the exact position of the item within that array you can find it with indexOf(). If the item does not exist within the array it will return -1, otherwise, it will return the index of that item within the array.
const follow = {
follower: ["5edfe8f3bfc9d677005d55ca",
"5edfe92fbfc9d677005d55cc",
"5ee2326cc7351c5bb0b75f1a"
]
}
const user = "5edfe92fbfc9d677005d55cc";
console.log(follow.follower.indexOf(user));
You are trying to compare a string to an array so it will never pass the if statement.
If you change your if to be if ( follower.includes(user)) { then it will search the array for the string.
var follower = [
'5edfe8f3bfc9d677005d55ca',
'5edfe92fbfc9d677005d55cc',
'5ee2326cc7351c5bb0b75f1a'
]
var user = '5edfe92fbfc9d677005d55cc'
// This will always fail as follower is an array not a string
if (follower.includes(user)){
console.log("sdasdsad")
} else {
console.log("no")
}
References
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes
Looks like follower is a property. You can use this solution:
objectName.follower.forEach(item =>
if (item == user) console.log(`${item} is the answer`);
);
This way, javascript will go through all of the elements in the array and print it out if it is matching with your user variable.
You can also use for loop or while loop for the same process, however, since you're using an array, forEach will be much more useful.
If this was not your question and I misunderstood your question, let me know, I'll see if I can help.
I hope this helps
var obj = {
follower: [ '5edfe8f3bfc9d677005d55ca',
'5edfe92fbfc9d677005d55cc',
'5ee2326cc7351c5bb0b75f1a'
]
};
var userId = '5edfe92fbfc9d677005d55cc';
function searchUser(object, user){
if(obj.follower.includes(user)){
return object.follower.filter(x => x == user);
} else {
return 'no';
}
};
console.log(searchUser(obj, userId));
You can use Array.protorype.some() to check if user exists in the follower array.
const obj = {
follower: [
"5edfe8f3bfc9d677005d55ca",
"5edfe92fbfc9d677005d55cc",
"5ee2326cc7351c5bb0b75f1a"
]
}
const user = "5edfe92fbfc9d677005d55cc";
if(obj.follower.some(item => item === user)) {
console.log("found")
} else{
console.log("no")
}
You can also get the item with Array.protorype.find() with the same way as above, just assign it to a variable
Array.prototype.some
Array.prototype.find
PS: I have already searched the forums and have seen the relevant posts for this wherein the same post exists but I am not able to resolve my issue with those solutions.
I have 2 json objects
var json1 = [{uid:"111", addrs:"abc", tab:"tab1"},{uid:"222", addrs:"def", tab:"tab2"}];
var json2 = [{id:"tab1"},{id:"new"}];
I want to compare both these and check if the id element in json2 is present in json1 by comparing to its tab key. If not then set some boolean to false. ie by comparing id:"tab1" in json2 to tab:"tab1 in json1 .
I tried using below solutions as suggested by various posts:
var o1 = json1;
var o2 = json2;
var set= false;
for (var p in o1) {
if (o1.hasOwnProperty(p)) {
if (o1[p].tab!== o2[p].id) {
set= true;
}
}
}
for (var p in o2) {
if (o2.hasOwnProperty(p)) {
if (o1[p].tab!== o2[p].id) {
set= true;
}
}
}
Also tried with underscore as:
_.each(json1, function(one) {
_.each(json2, function(two) {
if (one.tab!== two.id) {
set= true;
}
});
});
Both of them fail for some test case or other.
Can anyone tell any other better method or outline the issues above.
Don't call them JSON because they are JavaScript arrays. Read What is JSON.
To solve the problem, you may loop over second array and then in the iteration check if none of the objects in the first array matched the criteria. If so, set the result to true.
const obj1 = [{uid:"111", addrs:"abc", tab:"tab1"},{uid:"222",addrs:"def", tab:"tab2"}];
const obj2 = [{id:"tab1"},{id:"new"}];
let result = false;
for (let {id} of obj2) {
if (!obj1.some(i => i.tab === id)) {
result = true;
break;
}
}
console.log(result);
Unfortunately, searching the forums and reading the relevant posts is not going to replace THINKING. Step away from your computer, and write down, on a piece of paper, exactly what the problem is and how you plan to solve it. For example:
Calculate for each object in an array whether some object in another array has a tab property whose value is the same as the first object's id property.
There are many ways to do this. The first way involves using array functions like map (corresponding to the "calculate for each" in the question, and some (corresponding to the "some" in the question). To make it easier, and try to avoid confusing ourselves, we'll do it step by step.
function calculateMatch(obj2) {
return obj2.map(doesSomeElementInObj1Match);
}
That's it. Your program is finished. You don't even need to test it, because it's obviously right.
But wait. How are you supposed to know about these array functions like map and some? By reading the documentation. No one help you with that. You have to do it yourself. You have to do it in advance as part of your learning process. You can't do it at the moment you need it, because you won't know what you don't know!
If it's easier for you to understand, and you're just getting started with functions, you may want to write this as
obj2.map(obj1Element => doesSomeElementInObj1Match(obj1Element))
or, if you're still not up to speed on arrow functions, then
obj2.map(function(obj1Element) { return doesSomeElementInObj1Match(obj1Element); })
The only thing left to do is to write doesSomeElementInObj2Match. For testing purposes, we can make one that always returns true:
function doesSomeElementInObj2Match() { return true; }
But eventually we will have to write it. Remember the part of our English description of the problem that's relevant here:
some object in another array has a tab property whose value is the same as the first object's id property.
When working with JS arrays, for "some" we have the some function. So, following the same top-down approach, we are going to write (assuming we know what the ID is):
In the same way as above, we can write this as
function doesSomeElementInObj2Match(id) {
obj2.some(obj2Element => tabFieldMatches(obj2Element, id))
}
or
obj2.some(function(obj2Element) { return tabFieldMatches(obj2Element, id); })
Here, tabFieldMatches is nothing more than checking to make sure obj2Element.tab and id are identical.
We're almost done! but we still have to write hasMatchingTabField. That's quite easy, it turns out:
function hasMatchingTabField(e2, id) { return e2.tab === id; }
In the following, to save space, we will write e1 for obj1Element and e2 for obj2Element, and stick with the arrow functions. This completes our first solution. We have
const tabFieldMatches = (tab, id) { return tab === id; }
const hasMatchingTabField = (obj, id) => obj.some(e => tabFieldMatches(e.tab, id);
const findMatches = obj => obj.some(e => hasMatchingTabField(e1, obj.id));
And we call this using findMatches(obj1).
Old-fashioned array
But perhaps all these maps and somes are a little too much for you at this point. What ever happened to good old-fashioned for-loops? Yes, we can write things this way, and some people might prefer that alternative.
top: for (e1 of obj1) {
for (e2 of (obj2) {
if (e1.id === e2.tab) {
console.log("found match");
break top;
}
}
console.log("didn't find match);
}
But some people are sure to complain about the non-standard use of break here. Or, we might want to end up with an array of boolean parallel to the input array. In that case, we have to be careful about remembering what matched, at what level.
const matched = [];
for (e1 of obj1) {
let match = false;
for (e2 of obj2) {
if (e1.id === e2.tab) match = true;
}
matched.push(match);
}
We can clean this up and optimize it bit, but that's the basic idea. Notice that we have to reset match each time through the loop over the first object.
I'm currently writing a little function to take a $scope value from an input field, then add it to a new array containing invited users.
To prevent duplicate entries into the array I'm trying to use JavaScript's filter method.
My problem is when I look at whats being output to the console, the console.log inside the filter function always prints the same Email value, it doesn't seem to update and consider the new input. e.g. a user has added 2 users, the first will be added and the invitesArr will only contain the first Email.
var invitesArr = $scope.invites;
console.log(invitesArr)
console.log($scope.searchContacts)
if ($scope.invites.length >= 0) {
invitesArr.filter(function(invitesArr) {
console.log(invitesArr.Email)
return invitesArr.Email === $scope.searchContacts;
});
if (invitesArr == false) {
courseAccountService.inviteGuestToCourse($scope.courseId,$scope.searchContacts).
then(function(invitation) {
$scope.invites.push(invitation);
});
}
}
Try the below code:
var invitesArr = $scope.invites;
console.log(invitesArr)
console.log($scope.searchContacts)
if ($scope.invites.length >= 0) {
//use arrow operator instead of function.
var duplicateEmails = invitesArr.filter((item) => {
console.log(invitesArr.Email)
//assuming datatype of item.Email and $scope.searchContacts are same else use == for comparision
return item.Email === $scope.searchContacts;
});
//Check for length and then push to your invites
if (duplicateEmails.length==0) {
courseAccountService.inviteGuestToCourse($scope.courseId,$scope.searchContacts).
then(function(invitation) {
$scope.invites.push(invitation);
});
}
}
Hope it helps!!