I parsed a json and I'm trying to take 2 values for each element from the json and put them in a array the problem is that I want to put the values into the array like a single element "array" example:
[
{ name: 'name1', elements: [ 'elem1' ] },
{ name: 'name2', elements: [ 'elem2', 'elem3' ] }
]
I tried 2 ways.
the first is this:
function getMonsters(json) {
var monsters = [];
var monster = {};
json.forEach(element => {
if (element.type === "large") {
monster['name'] = element.name;
monster['elements'] = element.elements;
monsters.push(monster);
}
});
return monsters;
}
the problem with the first way is that it always returns the same 2 values:
the second way is this:
function getMonsters(json) {
var monsters = [];
var monster = {};
json.forEach(element => {
if (element.type === "large") {
monsters.push(element.name, element.elements);
}
});
return monsters;
}
but the problem with the second way is that it returns each monster and element separately and not like in my example:
this is the json if u want to check : https://mhw-db.com/monsters
You are reusing the monster object every iteration in your first example. Either move the declaration of var monster = {} into the loop or, better yet, just push an object literal.
function getMonsters(json) {
const monsters = [];
json.forEach(({ elements, name, type }) => {
if (type === "large") {
monsters.push({ name, elements });
}
});
return monsters;
}
Your first attempt is almost correct. The reason why all of the items in the array end up being the same object is because monster is the same reference in all of the array items. You need a new instance of monster on every iteration. Just put your initialization of monster in your loop
function getMonsters(json) {
var monsters = [];
json.forEach(element => {
if (element.type === "large") {
var monster = {};
monster['name'] = element.name;
monster['elements'] = element.elements;
monsters.push(monster);
}
});
return monsters;
Related
In the snippet below the goal is to check if the addedPlayer already exist in players by checking the .name property
if addedPlayer is already in players : Give the player a point
else update players by adding in addedPlayer with a starting point
let players = []
let addedPlayer = {
name: /* The Given Name To Check in players */ ,
points: 1
}
function addPlayer(playerList, playerToAdd){
const existingPlayers = playerList.map((playerToAdd) => playerToAdd.name);
if(existingPlayers.includes(playerToAdd.name)){
playerToAdd.points++
} else {
playerList.push(playerToAdd)
}
}
addPlayer(players, addedPlayer)
console.log(players)
The problem is players only returns addedPlayer. My Goal being that players will store every new player and adds points accordingly
You can achieve that by finding if the newPlayer already exists in the given array by checking against player.name then conditionally incrementing player.point if newPlayer already exists else adding the newPlayer to the array.
Here is an example.
let players = [
{
name: 'Player1',
point: 1
},
{
name: 'Player2',
point: 2
}
]
let newPlayer = {
name: 'Player2',
points: 1
}
function addPlayer(playerlist, newPlayer) {
// idx will be -1 if a player does not exist in playerlist by the name
const idx = playerlist.findIndex(p => p.name === newPlayer.name);
if (idx === -1) {
// if you want to mutate the original array you can use playerlist.push(newPlayer) then return immediately from the function and omit the next return line
return [...playerlist, newPlayer]
}
// increment player.point if newPlayer already exists
playerlist[idx] = {...playerlist[idx], point: playerlist[idx].point + 1}
// if you want to mutate the original array then omit the next return line
return [...playerlist]
}
// because newPlayer already exists in players array by name calling the function addPlayer will increment player.point in players array where player.name is 'Player2'
console.log(addPlayer(players, newPlayer))
// calling the function with a player that does not exist in the array
let anotherPlayer = { name: 'Player3', point: 0 };
// anotherPlayer will be added to the returned array
console.log(addPlayer(players, anotherPlayer))
P.S. - The current solution will return a new array on each call of the addPlayer function if your use case requires you to mutate the array you can use Array.prototype.push and omit the returns from the function. I have included some comments in the snippet for more details.
It's considered good practice to always initialize our variables. I just created a name variable for our user object.
Each time you run addPlayer it will now push new players to the list.
let players = []
var name = "";
let addedPlayer = {
name: name,
points: 1
}
function addPlayer(playerList, playerToAdd) {
const existingPlayers = playerList.map((playerToAdd) => playerToAdd.name);
if (existingPlayers.includes(playerToAdd.name)) {
playerToAdd.points++
} else {
playerList.push(playerToAdd)
}
}
addPlayer(players, addedPlayer)
console.log(players)
I have an object that has multiple keys and each of these keys has an array storing multiple elements. I want to be able to remove a specified element from the key's array.
I have tried using the delete keyword as well as the filter method, but I have been unsuccessful. I'm a total newbie to JS so I appreciate any assistance. Also, I want to do this using ONLY JavaScript, no libraries.
Here is the code where I am creating my object:
function add(task, weekdayDue) {
let capitalWeekday = weekdayDue.charAt(0).toUpperCase() +
weekdayDue.slice(1);
if (toDoList[capitalWeekday] === undefined) {
let subArr = [];
toDoList[capitalWeekday] = subArr.concat(task);
} else {
toDoList[capitalWeekday].push(task);
}
}
and here is the code as I have it now. Clearly it is not producing the correct result:
function remove(task, weekdayDue) {
let capitalWeekday = weekdayDue.charAt(0).toUpperCase() +
weekdayDue.slice(1);
delete toDoList.capitalWeekday[task]
//the below code is working; i want to send this to another
array
if (archivedList[capitalWeekday] === undefined) {
let subArr = [];
archivedList[capitalWeekday] = subArr.concat(task);
} else {
archivedList[capitalWeekday].push(task);
}
};
add('laundry', 'monday');
add('wash car', 'monday');
add ('vacuum', 'tuesday');
add('run errands', 'wednesday');
add('grocery shopping', 'wednesday');
// the output is: { Monday: [ 'laundry', 'wash car' ],
Tuesday: [ 'vacuum' ],
Wednesday: [ 'run errands', 'grocery shopping' ] }
Then let's say I want to remove 'wash car' from Monday I was trying:
remove('wash car', 'monday');
console.log(toDoList)
// The output is an empty object {}
I personally would refactor a bit your code, but I've worked a bit around it to fix some issues.
First of all, you shouldn't use delete for your scenario, because it will reset the item at the nth position of the array with the default value, which is undefined.
Usually, for that kind of operations, since you deal with strings, you rather take a look at the first occurrence of your item in the array, take its index, and use splice (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice) to actually remove the item from the array.
In this way, you end up with a clean array without invalid items in it.
Below is the working code (with the mentioned fixes) that does what you asked. As a side note, I would suggest you to avoid working with strings for such purposes, but I would rather tackle objects with unique ids, so that it's significantly easier to keep track of them between arrays and objects.
Additionally, there are some cases that you didn't think about, for instance I can think about calling remove by giving an invalid task, so you may work a bit around the code below to handle the case where taskIndex is -1 (meaning that no item was found with that index).
var toDoList = {}, archivedList = {};
function add(task, weekdayDue) {
let capitalWeekday = weekdayDue.charAt(0).toUpperCase() + weekdayDue.slice(1);
if (toDoList[capitalWeekday] === undefined) {
let subArr = [];
toDoList[capitalWeekday] = subArr.concat(task);
} else {
toDoList[capitalWeekday].push(task);
}
}
function remove(task, weekdayDue) {
let capitalWeekday = weekdayDue.charAt(0).toUpperCase() + weekdayDue.slice(1);
let taskIndex = toDoList[capitalWeekday].indexOf(task);
toDoList[capitalWeekday].splice(taskIndex, 1);
//delete toDoList[capitalWeekday][taskIndex];
if (archivedList[capitalWeekday] === undefined) {
let subArr = [];
archivedList[capitalWeekday] = subArr.concat(task);
} else {
archivedList[capitalWeekday].push(task);
}
};
add('test', 'monday');
add('wash car', 'monday');
remove('wash car', 'monday');
console.log(toDoList);
console.log(archivedList);
You are on the right path. Maybe the trouble you had with filter is because filter will return a new Array and not modify the current one. You could update your remove function and replace the line:
delete toDoList.capitalWeekday[task]
with
toDoList.capitalWeekday = toDoList.capitalWeekday.filter((item) => {return item !== task});
function remove(task, weekdayDue) {
let capitalWeekday = weekdayDue.charAt(0).toUpperCase() +
weekdayDue.slice(1);
// Assign new array with all elements but task
toDoList[capitalWeekday] = toDoList[capitalWeekday].filter(i => i !== task)
};
add('foo'...
add('bar'...
"{
"Baz": [
"Foo",
"Bar"
]
}"
remove('foo'...
"{
"Baz": [
"Bar"
]
}"
I have a program that pushes values into one data structure like this:
if(symbolType == "C" || symbolType == "P") // The calls and puts
stocks.push({
symbol: symbol,
undsymbol: undSymbol,
open: 0,
type: symbolType,
expiry: expiry,
days: days,
strike: strike
});
}
else // The stock
{
stocks.push({
symbol: symbol,
open: 0,
type: symbolType
});
}
So this is the key: NOT A STRING!
{
symbol: symbol,
open: 0,
type: symbolType
}
And the values of which are many look like this:
{
symbol: symbol,
undsymbol: undSymbol,
open: 0,
type: symbolType,
expiry: expiry,
days: days,
strike: strike
}
The problem is that stocks and calls and puts are being put into one collection. Instead, I want to add the the stocks and their corresponding calls and puts into a dictionary/map, where the stocks are the keys, and the calls and puts get pushed into an array indexed by it's stock.
At the end, I want to be able to iterate and get the keys and values.
How do I declare this object
Index into it to see if the key[stock] already exists, if it doesn't add it with an empty array.
If I get a "C" or "P", I want to get the corresponding array that holds the Calls/Puts for this key [stock] and push the call/put into the array.
Initially I thought the declaration was something like this:
var stockCallsPutDict = {[]}
stockCallsPutDict[stock] = [];
stockCallsPut[stock].push(call);
// Pretty print the dict of keys and its options =
stockCallsPutDict.forEach(function kvp) {
...
}
If ES6 is an option, you can either build an object yourself or use a Map.
Here's some quick code I came up with:
const stocks = {};
const addCallAndPut = callAndPut => {
const symbol = callAndPut.symbol;
if (!stocks[symbol]) {
stocks[symbol] = [];
}
stocks[symbol].push(callAndPut);
}
const showStuff = () => {
for (const symbol in stocks) {
// output stuff using stocks[symbol]
}
}
OR WITH A MAP
const stocks = new Map();
// basic implementation
const addCallAndPut = callAndPut => {
const stockCallsAndPuts = stocks.get(callAndPut.symbol) || [];
stockCallsAndPuts.push(callAndPut);
stock.set(callAndPut.symbol, stockCallsAndPuts);
}
There are a few ways to go about this, and the best depends on how the data needs to be processed later, but from your description I'd go with something along the lines of
var stocks = {};
var stockCallsPut = {};
// loop over stocks and actions
if (!(symbol in stocks)) {
stocks[symbol] = [];
}
if (!(symbol in stockCallsPut)) {
stockCallsPut[symbol] = {};
}
if (!(symbolType in stockCallsPut[symbol])) {
stockCallsPut[symbol][symbolType] = [];
}
// accumulated stock json items here
stocks[symbol].push(new_stock_item);
// accumulated push/call json items of stock here
stockCallsPut[symbol][symbolType].push(new_action);
I'm still not sure I actually understood what your data looks like, but sounds kind of like this to me:
// Not sure if data is an object or array
var data = {
'one': {
'name': 'one-somename',
'number': 'one-somenumber',
'symbol': 'C'
},
'two': {
'name': 'two-somename',
'number': 'two-somenumber',
'symbol': 'P'
},
'three': {
'name': 'three-somename',
'number': 'three-somenumber',
'symbol': 'C'
}
};
var stocks = {};
for (var name in data) {
// It sounded like you wanted a call/put array for each object but I'm not sure if that's true since it wouldn't be possible... if so can just divide this part up into it's appropriate place in the if statement below
// Checking that the property is set on the object, if it is, it uses itself, otherwise it adds it with the call/put arrays created
stocks[name] = stocks[name] ? stocks[name] : {'calls': [], 'puts': []};
var type;
if (data[name]['symbol'] === 'C') {
type = 'calls';
} else if (data[name]['symbol'] === 'P') {
type = 'puts';
}
stocks[name][type].push(data[name]);
}
I am using Ionic with AngularJS and I am using a localForage database and AJAX via $http. My app has a news stream that contains data like this:
{
"feed":[
{
"id":"3",
"title":"Ein Hund",
"comments:"1"
},
{
"id":"2",
"title":"Eine Katze",
"comments":"2"
}
],
"ts":"20150907171943"
}
ts stands for Timestamp. My app saves the feed locally via localForage.
When the app starts it first loads the locally saved items:
$localForage.getItem("feed").then(function(val) { vm.feed = val; })
Then, it loads the new or updated items (ts < current timestamp) and merges both the old and new data:
angular.extend(vm.feed, response.data.feed);
Updated items look like this:
{
"feed":[
{
"id":"2",
"title":"Eine Katze",
"comments":"4"
}
],
"ts":"20150907171944"
}
That is, the comments count on feed item 2 has changed from 2 to 4. When I merge the old and new data, vm.feed has two items with id = 2.
Does angularjs has a built-in "merge by id" function, i. e. copy from source to destination (if it is a new element), or otherwise replace the old element? In case angularjs does not have such a function, what's the best way to implement this?
Thanks in advance!
angular.merge(vm.feed, response.data.feed);
// EDIT
Probably, it will not merge correctly, so you have to update all properties manually. Update ts property and then find your object with id and replace it.
There is no builtin, I usually write my own merge function:
(function(){
function itemsToArray(items) {
var result = [];
if (items) {
// items can be a Map, so don't use angular.forEach here
items.forEach(function(item) {
result.push(item);
});
}
return result;
}
function idOf(obj) {
return obj.id;
}
function defaultMerge(newItem, oldItem) {
return angular.merge(oldItem, newItem);
}
function mergeById(oldItems, newItems, idSelector, mergeItem) {
if (mergeItem === undefined) mergeItem = defaultMerge;
if (idSelector === undefined) idSelector = idOf;
// Map retains insertion order
var mapping = new Map();
angular.forEach(oldItems, function(oldItem) {
var key = idSelector(oldItem);
mapping.set(key, oldItem);
});
angular.forEach(newItems, function(newItem) {
var key = idSelector(newItem);
if (mapping.has(key)) {
var oldItem = mapping.get(key);
mapping.set(key, mergeItem(newItem, oldItem));
} else {
// new items are simply added, will be at
// the end of the result list, in order
mapping.set(key, newItem);
}
});
return itemsToArray(mapping);
}
var olds = [
{ id: 1, name: 'old1' },
{ id: 2, name: 'old2' }
];
var news = [
{ id: 3, name: 'new3' },
{ id: 2, name: 'new2' }
];
var merged = mergeById(olds, news);
console.log(merged);
/* Prints
[
{ id: 1, name: 'old1' },
{ id: 2, name: 'new2' },
{ id: 3, name: 'new3' }
];
*/
})();
This builds a Map from the old items by id, merges in the new items, and converts the map back to list. Fortunately the Map object will iterate on the entries in insertion order, according to the specification. You can provide your idSelector and mergeItem functions.
Thanks hege_hegedus. Based on your code, I've written my own and tried to use less loops to speed things up a bit:
function updateCollection(localCollection, fetchedCollection) {
angular.forEach(fetchedCollection, function(item) {
var append = true;
for (var i = 0; i < localCollection.length; i++) {
if (localCollection[i].id == item.id) {
// Replace item
localCollection[i] = item;
append = false;
break;
} else if (localCollection[i].id > item.id) {
// Add new element at the right position, if IDs are descending check for "< item.id" instead
localCollection.splice(i, 0, item);
append = false;
break;
}
}
if (append) {
// Add new element with a higher ID at the end
localCollection.push(item);
// When IDs are descending use .unshift(item) instead
}
});
}
There is still room for improvements, i. e. the iteration through all the objects should use binary search since all items are sorted by id.
I have a JSON object like this...
{
"tasks":[
{
"id":"task_3",
"taskName":"Task A",
"assignee":"Barrack Obama",
"timeReqOptimisitic":"4",
"timeReqNormal":"8",
"timeReqPessimistic":"14",
"timeUnit":"Days",
"timeReq":"8.33",
"positionX":493,
"positionY":101,
"lockStatus":"unlocked"
}
],
"milestones":[
{
"id":"task_1",
"milestoneName":"Start",
"positionX":149,
"positionY":109,
"lockStatus":"unlocked",
"milestoneDate":"2015-04-07"
},
{
"id":"task_2",
"milestoneName":"Finish",
"positionX":989,
"positionY":367,
"lockStatus":"unlocked",
"milestoneDate":"2015-04-22"
}
],
"connections":[
{
"connectionId":"con_10",
"pageSourceId":"task_1",
"pageTargetId":"task_3"
},
{
"connectionId":"con_20",
"pageSourceId":"task_3",
"pageTargetId":"task_2"
}
]
}
...this is a minimal version. In practice, there are numerous items in "tasks", "milestones" and "connections".
I need to iterate through the object and determine the "id" of the "milestones" item with the lowest/earliest "milestoneDate", then identify the "connections" item that has the same value for its "pageSourceId" and return its "pageTargetId".
So in the above example:
Step 1) Iterate through the object and determine the "id" of the "milestones" item with the lowest/earliest "milestoneDate".
Answer: milestones.id = "task_1"
Step 2) Identify the "connections" item that has the same value for its "pageSourceId".
Answer: connections.pageSourceId = "task_1"
Step 3) Return its "pageTargetId".
Answer: "task_3"
I have a working example here. However, I would like to know if there is a way to accomplish this without using the extremely high start date and also in one loop.
As you are not parsing the same array on these two loops, there is no way to merge your loops.
Anyway, you can yet remove the loops to access to the arrays:
http://jsfiddle.net/gael/sruvtwre/2/
$.each(object.milestones, function( index, value ) {
if(startDate > parseDate(value.milestoneDate)) {
startDate = parseDate(value.milestoneDate);
id = value.id
}
});
$.each(object.connections, function( index, value ) {
if(id == value.pageSourceId) {
pageTargetId = value.pageTargetId;
}
});
May be also sorting, and indexing your datas. Then you would need no loops:
Elements in milestones should be sorted, so the earliest milestones element would be milestones[0].
Elements in connections should be indexed by their pageTargetId property, so the requested element should be connections[id].
Your two loops would become:
var pageTargetId= object.connections[ object.milestones[0].id ].pageTargetId;
http://jsfiddle.net/gael/sruvtwre/4/
As said in comments, sorting is not an optimal solution, even if that does not really matter for small sets.
Roughly, there is no no needs to sort all the datas, just the latest matters.
You can use array reduce method, as an comparable alternative to a simple loop:
var latestMilestone= object.milestones.reduce(function(milestone1, milestone2){
if( parseDate(milestone1.milestoneDate) > parseDate(milestone2.milestoneDate) )
return milestone1;
else
return milestone2;
//convert date to timestamp
function parseDate(date) {
var parts = date.split('-');
return Date.UTC(parts[0], parts[1]-1, parts[2]); // Note: months are 0-based
}
});
How about this:
Assuming you get the milestones.id = "task_1" in first loop; outside the loop we can have use jQuery grep. As connections will have unique pageSourceId, grep will return an array with only one object.
var filteredData = jQuery.grep('CONNECTIONS_ARRAY', function(element, index){
return element.pageSourceId == 'MILESTONES_ID'; // Which you get in the loop earlier
});
Then we can access pageTargetId like this:
if(filteredData.length){
filteredData[0].pageTargetId;
}
Try
var dates = []
, ids = []
, filtered = $.map(data.milestones, function(value, index) {
dates.push(new Date(value.milestoneDate).getTime());
ids.push(value.id);
if (dates.length === data.milestones.length) {
var id = ids[$.inArray(Math.min.apply(Math, dates), dates)]
, res = $.grep(data.connections, function(task, key) {
return task.pageSourceId === id
})[0].pageTargetId;
return res
}
})[0]; // `"task_3"`
var data = {
"tasks":[
{
"id":"task_3",
"taskName":"Task A",
"assignee":"Barrack Obama",
"timeReqOptimisitic":"4",
"timeReqNormal":"8",
"timeReqPessimistic":"14",
"timeUnit":"Days",
"timeReq":"8.33",
"positionX":493,
"positionY":101,
"lockStatus":"unlocked"
}
],
"milestones":[
{
"id":"task_1",
"milestoneName":"Start",
"positionX":149,
"positionY":109,
"lockStatus":"unlocked",
"milestoneDate":"2015-04-07"
},
{
"id":"task_2",
"milestoneName":"Finish",
"positionX":989,
"positionY":367,
"lockStatus":"unlocked",
"milestoneDate":"2015-04-22"
}
],
"connections":[
{
"connectionId":"con_10",
"pageSourceId":"task_1",
"pageTargetId":"task_3"
},
{
"connectionId":"con_20",
"pageSourceId":"task_3",
"pageTargetId":"task_2"
}
]
};
var dates = []
, ids = []
, filtered = $.map(data.milestones, function(value, index) {
dates.push(new Date(value.milestoneDate).getTime());
ids.push(value.id);
if (dates.length === data.milestones.length) {
var id = ids[$.inArray(Math.min.apply(Math, dates), dates)]
, res = $.grep(data.connections, function(task, key) {
return task.pageSourceId === id
})[0].pageTargetId;
return res
}
})[0];
document.write(filtered);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">
</script>