This question already has answers here:
Remove from JS object where key value is an empty array
(2 answers)
Closed 2 years ago.
I have got object of array. I am trying to check empty.
const data = {
test:[],
test2:[],
test1:["can"]
}
Here is my trying code:
const dataObj = Object.values(data)
console.log(dataObj)
my output would be :
const data = {
test1:["can"]
}
You can use Object.entries and Array#reduce methods.
const data = {
test: [],
test2: [],
test1: ["can"]
}
const res = Object.entries(data).reduce((obj, [k, v]) => {
if (v && v.length) obj[k] = v;
return obj;
}, {})
console.log(res)
Or with for...of loop.
const data = {
test: [],
test2: [],
test1: ["can"]
}
const res = {};
for (let [k, v] of Object.entries(data)) {
if (v && v.length) res[k] = v;
}
console.log(res)
const data = {
test: [],
test2: [],
test1: ["can"],
test3: ["hi"]
}
for (let [key, value] of Object.entries(data)) {
if (value.length) {
console.log(`${key}: not emty`)
} else {
console.log(`${key}: emty`)
}
}
Related
I have an array of object from which I am trying to get values using map operator but I am getting the whole json objects all I want is just array of values.
Below is my code:
const obj = [
{
a: {
b: 'Paul',
}
},
{
c: 'Byeeee',
}
];
obj.map((val) => console.log(val));
what I am getting is
{ a: { b: 'Paul' } }
{ c: 'Byeeee' }
What I want is:
['Paul','Byeeee']
Someone let me know how can I get the desired output.
You can do this recursively. You can first start off by grabbing the values of your object, and then loop through those using .flatMap(). If you encounter a value that is an object, you can recursively grab the values of that object by recalling your function. Otherwise, you can return the value. The advantage of using .flatMap() here is that when the recursive call returns an array, we don't end up with inner arrays, but rather the array gets flattened into one resulting array:
const obj = [{ a: { b: 'Paul', } }, { c: 'Byeeee', } ];
const getValues = (obj) => {
return Object.values(obj).flatMap(val => Object(val) === val ? getValues(val) : val);
}
console.log(getValues(obj));
you can use the following solution.
const data = [{ a: { b: 'Paul' } }, { c: 'Byeeee' }];
const flatObjectValues = (obj, result) => {
// recursive function to get object values
const objValues = Object.values(obj);
if (objValues?.length > 0) {
objValues.map((v) => {
if (typeof v === 'object' && !Array.isArray(v)) {
flatObjectValues(v, result);
} else {
result.push(v);
}
return v;
});
}
};
const updatedData = [];
data.map((x) => flatObjectValues(x, updatedData));
console.log('updatedData: ', updatedData);
You can use recursion with array.reduce, like fellowing.
function getAllValues(objuct) {
return objuct.reduce((acc, curr) => {
if (typeof curr === 'object') {
return [...acc, ...getAllValues(Object.values(curr))];
}
return [...acc, curr];
}, []);
}
A recursive solution could be:
const arr = [{a: {b: "Paul",},},{c: "Byeeee",},];
const flatArrOfObjects = (arr) => {
const values = [];
for (const i in arr) flatObj(arr[i], values);
return values;
};
const flatObj = (obj, result) => {
for (const [key, value] of Object.entries(obj)) {
if (typeof value === "object") flatObj(value, result);
else result.push(value);
}
};
console.log(flatArrOfObjects(arr));
This question already has answers here:
Filter object properties by key in ES6
(30 answers)
Closed 1 year ago.
I'm trying to create an object from object and list of properties.
const pick = (obj, ...fields) => {
return [...fields] = obj
};
How can I realise this?
Reduce the list of fields, and take the values from the original object:
const pick = (obj, ...fields) => fields.reduce((acc, field) => ({ ...acc, [field]: obj[field] }), {});
const obj = { a: 1, b: 2, c: 3 };
const result = pick(obj, 'a', 'c');
console.log(result);
You can use the in operator to ignore properties that don't exist on the original object:
const pick = (obj, ...fields) => fields.reduce((acc, field) => {
const value = obj[field];
if(field in obj) acc[field] = value;
return acc;
}, {});
const obj = { a: 1, b: 2, c: 3 };
const result = pick(obj, 'a', 'c', 'd');
console.log(result);
Try something like this:
const pick = (obj, ...fields) => Object.fromEntries(Object.entries(obj).filter(([k]) => fields.includes(k)))
Iterate through fields array and check if property is available in obj then put into final object which needs to be returned.
const pick = (obj, ...fields) => {
const finalObj = { };
for (field of fields) {
if (obj[field]) {
finalObj[field] = obj[field];
}
}
return finalObj;
};
const obj = { name: "test name", age: 25, title: "Mr.", city: "test city" };
console.log(pick(obj, "name", "age", "city", "other"));
I have an object like: const obj = { 'abc': {'def': 1 } } and I have an array like const arr = ['abc', 'def'] How can I access obj.abc.def property of my object with the array?
Obviously, obj[arr] doesn't work, also obj[arr.join('.') doesn't work.
What I want to do is:
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
const value = obj[arr] // crash
// value should contain 1
You could take a dynamic approach and reduce the keys and take a default object, if a part is not accessable.
const
getValue = (object, keys) => keys.reduce((o, k) => (o || {})[k], object),
obj = { abc: { def: 1 } },
arr = ['abc', 'def'],
value = getValue(obj, arr);
console.log(value);
console.log(getValue(obj, ['foo', 'bar']));
The base is
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
console.log(obj[arr[0]][arr[1]]);
or if you need to do it with a function...
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
function access(obj, arr) {
return arr.reduce((o, key) => o[key], obj);
}
console.log(access(obj, arr));
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
var value = obj;
for(let key of arr){
value = value[key];
}
console.log(value);
You can access the array property by index only. so arr[0] will work.
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
const value = obj[arr[0]][arr[1]]
console.log(value)
or you can run the loop over it.
const obj = { 'abc': {'def' : {'ghi': 1 } } };
const arr = ['abc', 'def', 'ghi'];
let ans = null;
for (let i=0; i<arr.length; i++) {
if(i==0) {
ans = obj[arr[0]];
}
else {
ans = ans[arr[i]];
}
}
console.log(ans)
You can use Array#reduce for a dynamic array.
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
const res = arr.reduce((o,prop)=>o[prop], obj);
console.log(res);
If you do not want errors to be thrown on properties that do not exist, you can use the optional chaining operator.
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def', 'notdefined', 'notdefined2']
const res = arr.reduce((o,prop)=>o?.[prop], obj);
console.log(res);
What you try to do is somewhat called object value "get by path", some library have support this and for example ramda is a production-ready library for that, you should not try to reinvent the wheel (practice is okay)
In your context, ramda's path method could help you achieve to the case of arbitrary array of properties
const obj = {
'abc': {
'def': 1,
'ghi': {
'jkl': 10
}
}
}
console.log(R.path(['abc', 'def'], obj))
console.log(R.path(['abc', 'ghi'], obj))
console.log(R.path(['abc', 'ghi', 'jkl'], obj))
console.log(R.path(['abc', 'ghi', 'jkl', 'mno'], obj))
<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>
I want to get the length of values from an object. If the value has no length i should get 0 length, if value exists i should get value.
const object1 = {
a: '',
b: '5'
};
function app() {
for (const [key, value] of Object.entries(object1)) {
console.log(key, value)
return {
[key]: !object1[key].length ? '0 length' : value
}
}
}
console.log(app())
Question:
Why i get just first value from object?
{
"a": "0 length"
}
expect:
{
"a": "0 length",
"b": 1
}
Why now i get in console.log(key, value) just the first value-key, but if i delete the return statement i get both value-key?
const object1 = {
a: '',
b: '5'
};
function app() {
for (const [key, value] of Object.entries(object1)) {
console.log(key, value)
// return {
// [key] : !object1[key].length ? '0 length' : value
// }
}
}
console.log(app())
Because you are returning from very first value inside for you are getting only one value in result.
Instead of that take one variable for ex let result = {}; Assign length values to it inside for as result[key] = value.toString().length || '0 length'; and then return result;.
Try it below.
const object1 = {
a: '',
b: '5'
};
function app() {
let result = {};
for (const [key, value] of Object.entries(object1)) {
// console.log(key, value)
result[key] = value.toString().length || '0 length';
}
return result;
}
console.log(app());
If your expected output is array then use like below. For array result you can also use map with like shown in app2.
const object1 = {
a: '',
b: '5'
};
function app() {
let result = [];
for (const [key, value] of Object.entries(object1)) {
result.push({[key]: value.toString().length || '0 length'});
}
return result;
}
function app2() {
return Object.entries(object1).map(([key, value]) => ({[key]: value.toString().length || '0 length'}));
}
console.log(app());
console.log(app2());
return exits the loop after first iteration
Perhaps you should do something like this
const object1 = {
a: '',
b: '5'
};
const newObj = {};
function app() {
for (const [key, value] of Object.entries(object1)) {
console.log(key, value)
newObj[key] = !object1[key].length ? '0 length' : value
}
return newObj;
}
console.log(app())
const object1 = {
a: '',
b: '5'
};
function app() {
const result = [];
for(let key in object1) {
if(object1[key] && object1[key].length) {
result.push({[key] :`${object1[key].length} length`});
} else {
result.push({[key] :`0 length`});
}
}
return result;
}
console.log(app())
I am trying to learn how to cope with the objects and arrays and I saw many ways of iterating objects but recursing doesn't work for me and I don't understand why. What am I doing wrong?
I need to loop through an object and just slightly change something in an array. In my case, it's uppercasing the keys
Here is what I've got for now
const development = {
port: 8080,
db: {
username: "jkdfs",
password: "dsfsdg",
name: "kslfjskd",
test: { test: 12, another: 'value' }
},
token_secret: "jfkjdsj",
hash_rounds: "kjsfkljdfkl"
};
function throughObject(obj) {
let collection = {};
for (const key in obj) {
if (obj.hasOwnProperty(key)) {
let value = obj[key];
if (typeof obj[key] !== 'object') {
collection[key.toUpperCase()] = value;
} else {
collection[key.toUpperCase()] = nestedObject(obj[key]);
}
}
function nestedObject(nested) {
const sub = {};
for (const k in nested) {
let v = nested[k];
if (typeof nested[k] !== 'object') {
sub[k.toUpperCase()] = v;
} else {
nestedObject(v);
}
}
return sub;
}
}
return collection;
}
const r = throughObject(development);
console.log(r);
When you're recursively calling the function on an object value, you still need to assign it to the sub object: sub[k.toUpperCase()] = nestedObject(v). Also, you don't need 2 different functions.
const development = {
port: 8080,
db: {
username: "jkdfs",
password: "dsfsdg",
name: "kslfjskd",
test: { test: 12, another: 'value' }
},
token_secret: "jfkjdsj",
hash_rounds: "kjsfkljdfkl"
};
function nestedObject(nested) {
const sub = {};
for (const k in nested) {
const v = nested[k];
if (typeof nested[k] !== 'object')
sub[k.toUpperCase()] = v;
else
sub[k.toUpperCase()] = nestedObject(v); // <- HERE
}
return sub;
}
console.log(nestedObject(development))
Here's a shorter version using Object.fromEntries()
const development={port:8080,db:{username:"jkdfs",password:"dsfsdg",name:"kslfjskd",test:{test:12,another:"value"}},token_secret:"jfkjdsj",hash_rounds:"kjsfkljdfkl"};
const convert = o =>
Object.fromEntries(
Object.entries(o).map(([k, v]) =>
[k.toUpperCase(), Object(v) === v ? convert(v) : v]
)
)
console.log(convert(development))