Related
I'm trying to merge 2 objects which contains arrays in one of their elements. I don't achieve the disered result when using spread syntax and the first object array is being replaced by the second one. The objects are like the following:
const objectA1 = {
keyA1:'valueA1',
keyArr:[{
arrKeyA01:'arrValueA01',
arrKeyA02:'arrValueA02',
},
{
arrKeyA11:'arrValueA11',
arrKeyA12:'arrValueA12',
}
]
}
const objectB1 = {
keyB1:'valueB1',
keyArr:[{
arrKeyB01:'arrValueB01',
arrKeyB02:'arrValueB02',
},
{
arrKeyB11:'arrValueB11',
arrKeyB12:'arrValueB12',
}
]
}
And I want to get:
const objectRes = {
keyA1:'valueA1',
keyB1:'valueB1',
keyArr:[{
arrKeyA01:'arrValueA01',
arrKeyA02:'arrValueA02',
arrKeyB01:'arrValueB01',
arrKeyB02:'arrValueB02',
},
{
arrKeyA11:'arrValueA11',
arrKeyA12:'arrValueA12',
arrKeyB11:'arrValueB11',
arrKeyB12:'arrValueB12',
}
]
}
What I'm using is
{...objectA1 ,...objectB1}
But as said, the keyArr doesn't keep the objectA1 elements.
How I can merge both objects and keep the array data using spread syntax?
Thanks for any comment/help :)
Create an object and place the first 2 values from A1 and B2 object. Customize the array separately by using reduce
const objectA1 = {
keyA1: 'valueA1',
keyArr: [{
arrKeyA01: 'arrValueA01',
arrKeyA02: 'arrValueA02',
},
{
arrKeyA11: 'arrValueA11',
arrKeyA12: 'arrValueA12',
}
]
}
const objectB1 = {
keyB1: 'valueB1',
keyArr: [{
arrKeyB01: 'arrValueB01',
arrKeyB02: 'arrValueB02',
},
{
arrKeyB11: 'arrValueB11',
arrKeyB12: 'arrValueB12',
}
]
}
const arr = objectA1.keyArr.reduce((acc, x) => {
const res1 = objectB1.keyArr.reduce((acc2, y) => ({...x,...y}), {})
return acc = [...acc, res1];
}, [])
const result = {
keyA1: objectA1.keyA1,
keyB1: objectB1.keyB1,
keyArr: arr
}
console.log(result)
I wanted to share my attemp solving this problem, I take the array and merge it in one using loops:
const objectA1 = {
keyA1:'valueA1',
keyArr:[{
arrKeyA01:'arrValueA01',
arrKeyA02:'arrValueA02',
},
{
arrKeyA11:'arrValueA11',
arrKeyA12:'arrValueA12',
}
]
}
const objectB1 = {
keyB1:'valueB1',
keyArr:[{
arrKeyB01:'arrValueB01',
arrKeyB02:'arrValueB02',
},
{
arrKeyB11:'arrValueB11',
arrKeyB12:'arrValueB12',
}
]
}
objects = [objectA1, objectB1];
let i = 0;
new_array = {};
for(i; i < objects.length; i++){
object = objects[i];
keys = Object.keys(object);
for(j = 0; j < keys.length; j++){
//if property already exists, example keyArr
this_key = keys[j];
console.log(this_key);
if(new_array[this_key] != undefined){
//loop through that property in the object
object[this_key].forEach((object_value, index) => {
//add all properties that previous object did not have
Object.assign(new_array[this_key][index], object_value);
});
}else{
//initialize that value with the first element array
new_array[this_key] = object[this_key];
}
}
}
console.log(objects);
console.log(new_array);
trialObject : {
'color': ['red','blue'],
'size': ['s','m'],
'material': ['cotton']
}
// RECURSION FUNCTION TO MAKE COMBINATIONS
makeObjectVariants(selected){
let key = Object.keys(selected)
if(Object.keys(selected).length === 1){
return selected[key[0]];
} else {
var result = [];
var currentArray = selected[key[0]]
delete selected[key[0]]
var restObjects = this.makeObjectVariants(selected) // call function again
for(var i = 0; i < restObjects.length; i++){
for (var j = 0; j < currentArray.length; j++) {
result.push([restObjects[i] +','+ currentArray[j]]);
}
}
return result; // resultant array
}
}
// OUTPUT
0:["cotton,s,red"]
1:["cotton,s,blue"]
2:["cotton,m,red"]
3:["cotton,m,blue"]
// EXPECTED OUTPUT
[{'material':cotton,'size':s,'color':red},...]
I want the output to contain key value pairs so that the array elements can be recognized which group they fall into.
I am facing problem in adding keys to the elements generated because m unable to keep track of the object keys
If you can use ES6 (default parameters, spread operator, arrow function, ...), the following code do the job:
var trialObject = {
color: ['red','blue'],
size: ['s','m'],
material: ['cotton']
};
var result = buildCombinations(trialObject);
console.log(result);
function buildCombinations(trialObject , keys = Object.keys(trialObject ), keyIndex = 0 , subObj = {}, res = []) {
trialObject[keys[keyIndex]].forEach(element => {
subObj[keys[keyIndex]] = element;
keys[keyIndex + 1] ? buildCombinations(trialObject , keys, keyIndex + 1, subObj, res) : res.push({...subObj});
});
return res;
}
I have an existing array of objects :
existingArray = [
{object1: 'object1'},
{object2: 'object2'}
{object3: 'object3'},
]
I receive a new one :
newArray = [
{object2: 'object2'},
{object3: 'object3'},
{object4: 'object4'}
]
I want only to modify the existing one to get the new one as the result (push+splice)
Here is what I have for now (is there a better way ?)
for (var i = 0; i < newArray.length; i++) {
// loop first to push new elements
var responseToTxt = JSON.stringify(newArray[i]);
var newStatement = false;
for(var j = 0; j < existingArray.length; j++){
var statementToTxt = JSON.stringify(existingArray[j]);
if(statementToTxt === responseToTxt && !newStatement){
newStatement = true;
}
}
if(!newStatement){
statements.push(response[i]);
}
}
var statementsToSplice = [];
for (var i = 0; i < existingArray.length; i++) {
// then loop a second time to split elements not anymore on the new array
var statementToTxt = JSON.stringify(existingArray[i]);
var elementPresent = false;
var element = false;
for(var j = 0; j < newArray.length; j++){
var responseToTxt = JSON.stringify(newArray[j]);
if(responseToTxt === statementToTxt && !elementPresent){
elementPresent = true;
} else {
element = i;
}
}
if(!elementPresent){
statementsToSplice.push(element);
}
}
Then I needed to split multiple times in the array :
existingArray = statementsToSplice.reduceRight(function (arr, it) {
arr.splice(it, 1);
return arr;
}, existingArray.sort(function (a, b) { return b - a }));
Here is the example :
https://jsfiddle.net/docmz22b/
So the final output should always be the new array, but only by push or splice the old one.
In this case, the final outpout will be
existingArray = [
{object2: 'object2'},
{object3: 'object3'}
{object4: 'object4'},
]
The new array could contains multiple new elements and/or deleted elements that is currently in the existingArray
Use shift() and push()
existingArray.shift(); //Removes the first element of the array
existingArray.push({'object4' : 'object4'});
Fiddle
I'm almost 100% sure that there is a better way to do it, but at least this works, feel free to comment any suggestions / optimizations.
existingArray = [
{object1: 'object1'},
{object2: 'object2'},
{object3: 'object3'}
];
newArray = [
{object2: 'object2'},
{object3: 'object3'},
{object4: 'object4'}
];
// Loop all the old values, if is not in the new array, remove it
existingArray.forEach(function(item) {
if(!inArray(item, newArray)) {
var idx = indexOfObjectInArray(item, existingArray);
existingArray.splice(idx, 1);
}
});
// Loop all the new values, if is not in the new array, push it
newArray.forEach(function(item) {
if (!inArray(item, existingArray)) {
existingArray.push(item);
}
});
// Auxiliar functions
function inArray(initialValue, array) {
testValue = JSON.stringify(initialValue);
return array.some(function(item) {
return testValue == JSON.stringify(item);
});
}
function indexOfObjectInArray(initialValue, array) {
var result = -1;
testValue = JSON.stringify(initialValue);
array.forEach(function(item, idx) {
if (testValue == JSON.stringify(item)) {
result = idx;
};
});
return result;
}
Maybe this helps. It features Array.prototype.forEach and Array.prototype.some.
Splice unwanted items
Look if object with same property exist
If yes, then assign new object
Else push the object
var existingArray = [
{ object1: 'object1' },
{ object2: 'object2' },
{ object3: 'object3' },
],
newArray = [
{ object2: 'object22' },
{ object3: 'object33' },
{ object4: 'object44' }
];
function update(base, change) {
var changeKeys = change.map(function (a) { return Object.keys(a)[0]; }),
i = 0;
while (i < base.length) {
if (!~changeKeys.indexOf(Object.keys(base[i])[0])) {
base.splice(i, 1);
continue;
}
i++;
}
change.forEach(function (a) {
var aKey = Object.keys(a)[0];
!base.some(function (b, i, bb) {
if (aKey === Object.keys(b)[0]) {
bb[i] = a; // if that does not work, use bb.splice(i, 1, a);
return true;
}
}) && base.push(a);
});
}
update(existingArray, newArray);
document.write('<pre>' + JSON.stringify(existingArray, 0, 4) + '</pre>');
I am new to JavaScript and wondering how can I compare an array with another array consists of JavaScript objects.
The array is a series of sorted time in the "YYYY-MM-DD" format.
The array of objects missed some price values of several days.
I want to find the missed value and assign it as "NULL".
For example, I have an array as:
array = ['2014-10-09','2014-10-10','2014-10-11','2014-10-12'];
and an array with objects as:
objArray = [{
date:"2014-10-09",
price:"100"
},
{
date:"2014-10-10",
price:"99"
},
{
date:"2014-10-12",
price:"102"
}];
I want to get the price array in this way:
priceResult = [100, 99, "NULL", 102];
What would be the most efficient way without using other libraries? I wanted to see if anyone had a more elegant solution. I deeply appreciate your help.
You can create a lookup set from the object array, then you can use that to translate the dates to prices.
This scales well, as it is an O(n+m) solution rather than the O(n*m) solution that you get if you use a loop in a loop to find the prices.
var array = ['2014-10-09','2014-10-10','2014-10-11','2014-10-12'];
var objArray = [{ date:"2014-10-09", model:"A", price:"100" },{ date:"2014-10-10", model:"A", price:"99" },{ date:"2014-10-12", model:"A", price:"102" }];
var lookup = {};
for (var i = 0; i < objArray.length; i++) {
lookup[objArray[i].date] = parseInt(objArray[i].price, 10);
}
var priceResult = [];
for (var i = 0; i < array.length; i++) {
if (lookup.hasOwnProperty(array[i])) {
priceResult.push(lookup[array[i]]);
} else {
priceResult.push('NULL');
}
}
// output result in StackOverflow snippet
document.write(JSON.stringify(priceResult));
Note: Instead of the string 'NULL' you might want to use the value null instead, as it is generally easier to handle.
lodash is the best library for this. But you did say "without using other libraries", so you will need to do it natively.
The easiest way to do it is nested for loops:
var i, j, d, res = [];
for (i=0; i<dateArray.length; i++) {
d = dateArray[i];
for (j=0; j<objArray.length; j++) {
if (objArray[j] && objArray[j].date && objArray[j].date === d) {
res.push(objArray[j].price);
j = objArray.length; // don't waste energy searching any more, since we found it
}
}
}
// res now contains all you wanted
If objArray is really big, and you don't want to search it multiple times, then you could turn it into an object indexed by date:
var i, obj = {}, d, res = [];
for (i=0; i<objArray.length; i++) {
if (objArray[i] && objArray[i].date) {
obj[objArray[i].date] = objArray[i];
}
}
for (i=0; i<dateArray.length; i++) {
d = dateArray[i];
res.push(obj[d] ? obj[d].price : null : null);
}
// res now contains all you wanted
Loop trough the object and search for the date in your array
// Add contains to array proto: http://css-tricks.com/snippets/javascript/javascript-array-contains/
var priceResult = [];
for(var i in objArray) {
if(dateArray.contains(objArray[i].date)) priceResult.push(objArray[i].date));
}
console.log('matches:', priceResult);
This function will give you map of all individual arrays in your object array
function getArrayMap(array) {
var map={}
for(var i=0;i<array.length;i++){
var o = array[i];
for(var k in o){
if(!map[k]){
map[k]=[];
}
map[k].push(o[k]);
}
}
return map;
}
you can use it like -
var map = getArrayMap(objArray);
console.log(map["date"]);//date array
console.log(map["price"]);//price array
console.log(map["model"]);//model array
If i am understanding your question correctly, for all the values in array, you want to check the objArr and find the price for each date, and if not found u want to inset null. If this is what you want, then following will help
var found= false;
var list=[];
for(var i=0; i< dateArray.length; i++)
{
for(var j=0; j< objArray.length; j++)
{
if(objArray[j].date == dateArray[i])
{
list.push(objArray[j].price);
found = true;
}
}
if(!found)
{
list.push("null");
}
found = false;
}
alert(list);
(I'm going to call your first array dates rather than array, to avoid confusion.)
There are basically two options:
Loop through your dates array and, for each entry, loop through the objArray looking for a match, and when found add to your priceResult array, or
Build a map from your objArray, then loop through yourdatesarray once, building thepriceResult` array.
Looping and Looping
You can loop through your dates array using forEach, and you can use Array#some to find out whether your objArray contains the date and add to priceResult if so (it's an ES5 feature, but you can polyfill it for really old browsers):
var priceResult = [];
dates.forEach(function(date) {
objArray.some(function(object) {
if (object.date == date) {
priceResult.push(object.price);
return true;
}
});
});
Array#some keeps looping until you return true, which is why we do that when we find the firs tmatch. That's why I say this is "looping and looping," even though we only write one loop, the other is within Array#some.
var dates = ['2014-10-09', '2014-10-10', '2014-10-11', '2014-10-12'];
var objArray = [
{
date: "2014-10-09",
model: "A",
price: "100"
},
{
date: "2014-10-10",
model: "A",
price: "99"
},
{
date: "2014-10-12",
model: "A",
price: "102"
}
];
// Do it
var priceResult = [];
dates.forEach(function(date) {
objArray.some(function(object) {
if (object.date == date) {
priceResult.push(object.price);
return true;
}
});
});
snippet.log(priceResult.join(", "));
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>
Mapping and Looping
First, create a map of prices by date:
var prices = {};
objArray.forEach(function(object) {
prices[object.date] = object.price;
});
...then create your results:
var priceResult = [];
dates.forEach(function(date) {
if (prices.hasOwnProperty(date)) {
priceResult.push(prices[date]);
}
});
var dates = ['2014-10-09', '2014-10-10', '2014-10-11', '2014-10-12'];
var objArray = [
{
date: "2014-10-09",
model: "A",
price: "100"
},
{
date: "2014-10-10",
model: "A",
price: "99"
},
{
date: "2014-10-12",
model: "A",
price: "102"
}
];
// Create the map
var prices = {};
objArray.forEach(function(object) {
prices[object.date] = object.price;
});
// Create your results:
var priceResult = [];
dates.forEach(function(date) {
if (prices.hasOwnProperty(date)) {
priceResult.push(prices[date]);
}
});
// Show them
snippet.log(priceResult.join(", "));
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>
var dates = ['2014-10-09','2014-10-10','2014-10-11','2014-10-12'];
var objArray = [{date:"2014-10-09", model:"A", price:"100" }, {date:"2014-10-10", model:"A", price:"99" }, {date:"2014-10-12", model:"A", price:"102" }];
var val;
var priceResult = [];
for (var a in dates) {
val = null;
for (var b in objArray) {
if (dates[a] == objArray[b].date) {
val = objArray[b].price;
}
}
priceResult.push(val);
}
var dates = ['2014-10-09', '2014-10-10', '2014-10-11', '2014-10-12'];
var objArray = [{
date: "2014-10-09",
model: "A",
price: "100"
}, {
date: "2014-10-10",
model: "A",
price: "99"
}, {
date: "2014-10-12",
model: "A",
price: "102"
}];
var val;
var priceResult = [];
for (var a in dates) {
val = null;
for (var b in objArray) {
if (dates[a] == objArray[b].date) {
val = objArray[b].price;
}
}
priceResult.push(val);
}
// output result in StackOverflow snippet
document.write(JSON.stringify(priceResult));
Try this:
var temp[]
temp= jQuery.grep(objArray , function (n, i)
{
for(j=0;j<dateArray.lenght+j++ )
if( n.date === dateArray[j])
return n.price;
);
dateArray = ["2014-10-09", "2014-10-10", "2014-10-11", "2014-10-12"];
function ObjectExample(date1,model,price)
{
this.date1 = date1;
this.model = model;
this.price = price;
}
var objArray = [new ObjectExample("2014-10-09","A","100"), new ObjectExample("2014-10-10","A","99"), new ObjectExample("2014-10-12","A","102")];
var i = 0;
var priceDate = new Array();
var count = 0;
while(i < dateArray.length)
{
var j = 0;
while(j < objArray.length)
{
if(dateArray[i] == objArray[j].date1)
{
priceDate[count] = objArray[j].price;
break;
}
else priceDate[count] = "NULL";
j = j + 1;
}
i = i + 1;
count++;
}
document.write(priceDate);
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Delete from array in javascript
I have the following JSON object:
[id:84,id:92,id:123,id:2353]
How would I go about removing the item which the value is "123" using javascript?
or if I formatted the json as
[84, 92, 123, 2353]
How would it be removed in this case?
Assume you have this:
var items = [{ id: 84 }, { id: 92 }, { id: 123 }, { id: 2353 }];
var filtered = items.filter(function(item) {
return item.id !== 123;
});
//filtered => [{ id: 84 }, { id: 92 }, { id: 2353 }]
Supposing you actually have an object from a json in the json variable
for (key in json) {
if (json.hasOwnProperty(key) && json[key] == 123) {
delete json[key];
}
}
Shorter alternative would be:
var newArr = [{id:84}, {id:92}, {id:123}, {id:2353}].filter(function(a) {
return a.id != 123;
});
If you have this:
var arr = [{id:84}, {id:92}, {id:123}, {id:2353}]
To remove the item with value 123, you can do:
for(var i = 0; i < arr.length; i++) {
if(arr[i].id == 123) {
arr.splice(i, 1);
break;
}
}
function removeClass(obj, cls) {
var classes = obj.className.split(' ');
for(i=0; i<classes.length; i++) {
if (classes[i] == cls) {
classes.splice(i, 1);
i--; // (*)
}
}
obj.className = classes.join(' ');
}
var obj = { className: 'open menu menu' }
removeClass(obj, 'menu')
alert(obj.className)
You can use splice function, like this:
var data = [{id:84}, {id:92}, {id:123}, {id:2353}];
function remove(){
for(var i = 0, max = data.length; i < max; i++) {
var a = data[i];
if(a.id === 123) {
data.splice(i, 1);
break;
}
}
}
remove();
Seems like you want to avoid a loop. Assuming it's available, you can use .filter:
[{id:84},{id:92},{id:123},{id:2353}]
.filter(function (elem) { return elem.id !== 123; });
This technically does do a loop, but at least you don't have to look at it.
Assuming your "json" is really an array, like [84, 92, 123, 2353]:
var myString = "[84, 92, 123, 2353]";
var myArray = JSON.parse(myString);
var index = myArray.indexOf(123); // whatever value you are looking for
myArray.splice(index, 1);
http://jsfiddle.net/7vkK6/
Assuming I'm understanding your question and comments correctly you can do something like this:
var old_array = [{id: 84},...];
var new_array = [];
for(var i = 0, len = old_array.length; i++) {
if (old_array[i].id != 123) new_array.push(old_array[i]);
}
What you have currently is not JSON so I'll give you some different options.
If you have an Array arr = [84,92,123,2353] then
arr = arr.filter(function (x) {return x !== 123;}); // all occurrences
// OR
arr.splice(arr.indexOf(123), 1); // first occurrence only
If you have an Object obj = {"84": a, "92": b, "123": c, "2353": d}, a to d some expressions, then
delete obj['123']; // obj now {"84": a, "92": b, "2353": d}
1) JSON is a string, not an array or an object.
var json = "[1,2,3]";
2) Valid JSON NEEDS to be valid JS
var myJSObj = { 1,2,3 }, // broken
myJSArr = [ name : 1, name2 : 2 ]; // broken
3) If you have a JS Array, you can remove an element by using [].splice
var arr = [ 1, 2, 3, 4 ],
i = 0, l = arr.length,
test = 4;
for (; i < l; i += 1) {
if (arr[i] === test) { arr.splice(i, 1); } // remove 1 starting at i
}
4) If you have an object with named keys, you can use delete
var obj = { val : 1 };
delete obj.val;