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JS: How to insert object into array alphabetically by key? [duplicate]

This question already has answers here:
How can we custom sort JavaScript object keys?
(3 answers)
Closed 24 days ago.
I have the following Javascript object:
let obj = {
a: 1,
b: 2,
d: 4
}
obj["c"] = 3
When I log this, the keys are in the order a, b, d, c. Is there a way to make it so that c is inserted between b and d?

One method is to create a new object with Object.fromEntries after sorting the entries of the original object.
let obj = {
a: 1,
b: 2,
d: 4
}
obj["c"] = 3;
let newObj = Object.fromEntries(Object.entries(obj).sort());
console.log(newObj);
Alternatively, just sort the keys before looping over them.
let obj = {
a: 1,
b: 2,
d: 4
}
obj["c"] = 3;
for (const key of Object.keys(obj).sort()) {
console.log(key, '=', obj[key]);
}

Adding or appending object with object javascript

i am having 2 objects and the code is
Object 1
var existingValue=self.get('objHubDto').ftd.gridDataDTO.gridDTOMap[name].gridDataMap;
Object 2
var newValue = self.get('childDataList')
I need to merge/add/append this two in newvalue value eventhough it having duplicate key values

Following is a very basic example to merge by keeping both values, however, you can create new object rather mutating existing one.
let obj1 = { a: 1, b: 2, c: 3 };
let obj2 = { a: 9, d: 8, e: 7 };
Object.entries(obj2).forEach(([key, val]) => {
obj1[key] = obj1[key] ? [obj1[key], val] : val;
});
console.log(obj1);

JavaScript/Coffeescript sum objects

I would love to "add/merge" (not sure how to call that) some objects in this manner:
obj1 = {
a: 1,
b: 1,
c: 1
}
obj2 = {
a: 1,
b: 1
}
obj1 + obj2 => { a: 2, b: 2, c: 1 }
Is there any way of achieving this? Tried, Object.assign(obj1, obj2) but It will not add properties like I need it to be done (it returns in { a: 1, b: 1, c: 1})

There isn't a built-in way to do it but you can enumerate the properties of one object and add their values to another.
const a = { a: 1, b: 1, c: 1 };
const b = { a: 1, b: 1 };
for(const prop in b) {
a[prop] = (prop in a ? a[prop] : 0) + b[prop];
}
console.log(a);
The prop in a check is so that we don't end up with NaN by adding undefined to the value in b.
You could use reduce to combine n number of objects like so:
const a = { a: 1, b: 1, c: 1 };
const b = { a: 1, b: 1 };
const c = { a: 1, c: 1 };
const result = [a, b, c].reduce((p, c) => {
for(const prop in c) {
p[prop] = (prop in p ? p[prop] : 0) + c[prop];
}
return p;
}, {});
console.log(result);
You didn't mention how you wanted to deal with properties in the prototype chain. You should know that for...in will enumerate properties in the prototype chain and prop in x will also examine the prototype chain. If your only want to enumerate the objects own properties then you could use Object.entries() to get its own properties or do a hasOwnProperty(...) check within the for...in and in place of the prop in x check. If you don't do any prototypal inheritance with your models then you may not care.

A quick answer:
let sum = {};
let keys = new Set(Object.keys(obj1))
Object.keys(obj2).map(x => keys = keys.add(x))
keys.forEach(x => {
let op1 = obj1[x] || 0;
let op2 = obj2[x] || 0;
sum[x] = op1 + op2;
})

Create an empty object:
var obj3 = {};
Use the spread operator to grab all the keys from both objects, then add them to the new object like so:
for(var i in {...obj1, ...obj2}) {
obj3[i] = (obj1[i] || 0) + (obj2[i] || 0);
}
var obj1 = {
a: 1,
b: 1,
c: 1
}
var obj2 = {
a: 1,
b: 2,
d: 3
}
var obj3 = {};
for(var i in {...obj1, ...obj2}) {
obj3[i] = (obj1[i] || 0) + (obj2[i] || 0);
}
console.log(obj3);

How to check if one Object partially contains another? [closed]

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So i am trying to check if one object contains exactly another/ partial. For example, i want to check if { a: 1, b: 2, c: 2 } contains { a: 1, b: 2 }. But has to be in that order. If a is the first element and lines up, the b element will have to line up exactly afterwards. Plus is their anyway i could check there value? Order does matter.
//Here is my code currently:
function whatIsInAName(collection, source) {
var array = [];
var sourceNames = Object.getOwnPropertyNames(source);
for (var i = 0; i < collection.length; i++) {
var collectionNames = Object.getOwnPropertyNames(collection[i])
JSON.stringify(collectionNames).includes(JSON.stringify(sourceNames)) ? array.push(collection[i]) : null
}
return array
}
whatIsInAName([{ a: 1, b: 2 }, { a: 1 }, { a: 1, b: 2, c: 2 }], { a: 1, b: 2 });
Its a exact check but, only for the names. I wish it also compared the values.
It also isn't partially checking for the object in another. Like comaparing { a: 1, b: 2, c: 2 } to contain { a: 1, b: 2 }
Here was the challenge i was given --> https://www.freecodecamp.org/challenges/wherefore-art-thou

You coukd take the keys of the single object for comparing the values and use every for returning the result for filtering the array of objects.
Array#filter for getting parts of the array,
Object.keys for getting an array with own keys of the object,
Array#every`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every) for checking all keys and values,
in operator for check if the key exist in the object,
Identity/strict equality operator === for checking type and value of the operands.
function compare(array, object) {
return array.filter(function (o) {
return Object.keys(object).every(function (k) {
return k in o && object[k] === o[k];
});
});
}
console.log(compare([{ a: 1, b: 2 }, { a: 1 }, { a: 1, b: 2, c: 2 }], { a: 1, b: 2 }));
.as-console-wrapper { max-height: 100% !important; top: 0; }

I was trying to guide you to figure out the problem on your own in the comments, but if you're just looking for a solution, here is how you can do this using basic JavaScript constructs (nothing fancy like Array#filter and Array#every).
It may be much longer than some other solutions, but it makes use of the basics of JavaScript:
function whatIsInAName(collection, source) {
var array = [];
var sourceNames = Object.getOwnPropertyNames(source);
// loop over each item in collection
for (var i = 0; i < collection.length; i++) {
var matchedProperties = 0;
// loop over each property in source
for (var j = 0; j < sourceNames.length; j++) {
// check whether the property is in collection[i] and
// whether the value matches
if (collection[i].hasOwnProperty(sourceNames[j]) &&
source[sourceNames[j]] === collection[i][sourceNames[j]]) {
matchedProperties += 1;
}
// add to array if all properties matched
if (matchedProperties === sourceNames.length) {
array.push(collection[i]);
}
}
}
return array
}
var result = whatIsInAName([{ a: 1, b: 2 }, { a: 1 }, { a: 1, b: 2, c: 2 }], { a: 1, b: 2 });
console.log(result);

Use lodash to apply a function to filtered properties of an object

I'd like to use lodash to selectively mutate properties in an object.
var foo = { 'a': 1, 'b': 2, 'c': 3 };
function addOne(num) {
return num + 1;
}
var propsToTransform = ['a', 'b'];
_(foo).pick(propsToTransfrom)
.map(addOne);
// I want foo = { 'a': 2, 'b':3, 'c':3 }
Is it possible to achieve this using the kind of composition I've outlined above or should I stick to something like
_.forEach(propsToTransform, (prop) => {
if (foo[prop]) {
foo[prop] = addOne(foo[prop]);
}
});

You are looking for _.mapValues and _.protoype.value as andlrc pointed out. You'll end up creating a new object with the new values and merge it with the original one :
var foo = { 'a': 1, 'b': 2, 'c': 3 };
var propsToTransfrom = ['a', 'b']
// Create a new object with the new, modified values and merge it onto the original one
var bar = _.merge(foo, _(foo).pick(propsToTransfrom).mapValues(addOne).value());
console.log(bar); // { 'a': 2, 'b': 3, 'c': 3 }
function addOne(num) {
return num + 1;
}