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what can i do i got out when i am searching class then count how many student in class

let student = [{
id:1,
name:'aman',
class:'10',
gender:'male'
},{
id:2,
name:'shivani',
class:'10',
gender:'female'
},{
id:2,
name:'riyan',
class:'11',
gender:'female'
}]
function customFilter(objList, text){
if(undefined === text || text === '' ) return objList;
return objList.filter(product => {
let flag;
for(let prop in product){
if(product[prop].toString().indexOf(text)>-1){
product[prop] = 0
product[prop]++
flag = product[prop]
console.log(flag)
}
}
return flag;
});}
console.log( customFilter(student, '10'))
I want the output of the number of students in a class. Example: when I pass class 10 as an argument then i should get output how many students in class 10
output:
{class:10,stduent:5 }

I didn't get your question well, but I assumed you want number of student in a class like this {class:10, students: 2}
let student = [
{ id:1, name:'aman', class:'10', gender:'male'},
{ id:2, name:'shivani', class:'10', gender:'female' },
{ id:3, name:'riyan', class:'11', gender:'female' }
]
function customFilter(objList, text){
if(undefined === text || text === '' ) return objList;
const numberOfStudents = objList.filter(product => {
for (let prop in product) {
if (product[prop].toString().includes(text)) {
return true;
}
}
});
return {class:text, student:numberOfStudents.length }
}
console.log( customFilter(student, '10'))
If that's the case this code will do , hope it helps

This would also work:
let students = [
{ id: 1, name: "aman", class: "10", gender: "male" },
{ id: 2, name: "shivani", class: "10", gender: "female" },
{ id: 2, name: "riyan", class: "11", gender: "female" },
];
const customFilter = (students, key, value) => {
const res = { [key]: value, student: 0 };
students.forEach((student) => {
if (student[key] === value) {
res.student += 1;
}
});
return res;
};
console.log(customFilter(students, "class", "10"));
Using Array.prototype.forEach()

There are few problems with the code. change class:'10' to grade: 10,.
don't use "class" as a variable name. might cause a few errors
There is a missing ,
numbers shouldn't be inside quotes because the number will be stored as a string
let student = [
{ id: 1, name: 'aman', grade: 10, gender: 'male'},
{ id: 2, name: 'shivani', grade: 10, gender: 'female' },
{ id: 2, name: 'riyan', grade: 11, gender: 'female' },
]
function customFilter(objList, value){
if(!value || value === '') return objList;
let count = 0
objList.forEach(obj => {
const { grade } = obj;
if(grade === value){
count++;
}
})
return {grade: 10, count};
}
console.log(customFilter(student, 10));
and forEach can be used instead of filter. It loops from start to end of an array

Use .reduce() to group all objects that match.
/* hits (accumulator) is initially an empty array.
now (current) is the object of the current iteration. */
array.reduce((hits, now) => { //...
On each iteration, get all of the current object's values (in lower case) in an array.
Object.values(now).map(val => val.toLowerCase())
/* result of the first object: ["01gn3z1ryjjqhn588ax3bws6qb", "theo bramstom",
"genderqueer", "english"] */
If any of the values of the current object matches the given string (term), add the current object to the hits array.
if (Object.values(now)
.map(val => val.toLowerCase()).includes(term.toLowerCase())) {
hits.push(now);
}
An object literal is returned.
{
"matches": /* an array of all matched objects */,
"total": /* the .length of "matches" array */
};
/* To get the answer prompted in OP -- do the following */
const x = dataFilter(students, "Math");
console.log(x.total);
// NOTE: key "class" is now "subject" just for aesthetics
const students=[{id:"01GN3Z1RYJJQHN588AX3BWS6QB",name:"Theo Bramstom",gender:"Genderqueer",subject:"English"},{id:"01GN3Z1RYM527HAX56ZN14F0YB",name:"Juli Marsy",gender:"Female",subject:"History"},{id:"01GN3Z1RYPYP1FFFEY55T92VX2",name:"Linc Espley",gender:"Non-binary",subject:"Math"},{id:"01GN3Z1RYR325M0QETVVPE2N5J",name:"Barbabas Grisley",gender:"Male",subject:"Math"},{id:"01GN3Z1RYTXA49SBQYXR9DMC04",name:"Godfree Braybrook",gender:"Male",subject:"English"},{id:"01GN3Z1RYVE4N5D16C8QWB1XGF",name:"Jason De Vuyst",gender:"Male",subject:"History"},{id:"01GN3Z1RYXY9WXF1Y407HXFYH8",name:"Adler McCanny",gender:"Male",subject:"Math"},{id:"01GN3Z1RYY9XV444J0SP5Y0QC2",name:"Noellyn MacMorland",gender:"Genderqueer",subject:"Math"},{id:"01GN3Z1RZ0HPQNZ1VKX8ZHA9ZY",name:"Padget Geldeford",gender:"Male",subject:"Math"},
{id:"01GN3Z1RZ2DZE92NG42KSGDXN9",name:"Milissent Treby",gender:"Female",subject:"Art"}];
const dataFilter = (array, term) => {
let result = array.reduce((hits, now) => {
if (Object.values(now).map(val => val.toLowerCase()).includes(term.toLowerCase())) {
hits.push(now);
}
return hits;
}, []);
return {"matches": result, "total": result.length};
}
console.log(dataFilter(students, "Math"));
// Control case: term === "Math"
console.log(dataFilter(students, "PE"));
// No match case: term != "PE"
console.log(dataFilter(students, "female"));
// Case insensitive case: term === "Female"

Javascript : Add Key & Value at specific index in array of Object

I have array of Object like this.
let arr = [{name:"abc",age:26},{name:"xyz",age:23},{name:"pqr",age:10}]
let newVal = arr.map(function(el) {
if(el.age > 25){
var o = Object.assign({}, el);
o.gender = 'male';
return o;
}
})
console.log("New Val : " , newVal)
I would like to add {gender:'male'} to object where age is > 25
It says undefined to other objects.
Any help would be great.
Thank You.

You need to return the value if the object doesn't match the condition. Since you haven't retrned anything from from inside map if the condition is not fulfilled, you get undefined for the other objects
let arr = [{
name: "abc",
age: 26
}, {
name: "xyz",
age: 23
}, {
name: "pqr",
age: 10
}]
let newVal = arr.map(function(el) {
if (el.age > 25) {
var o = Object.assign({}, el);
o.gender = 'male';
return o;
}
return el; // return value here
})
console.log("New Val : ", newVal)

issue with your code is already solved in other answer by Shubham, ie when if clause is not executed you are not returning anything.
but i think forEach might be cleaner here
if you want to keep the original array you can copy it using copyArr = [...arr]
let arr = [{name:"abc",age:26},{name:"xyz",age:23},{name:"pqr",age:10}]
arr.forEach(function(el) {
if(el.age > 25)
el.gender = 'male';
})
console.log("New Val : " , arr)

It's missing the return statement when the condition is false.
You can do this in one line using an arrow function as follow:
let arr = [{name:"abc",age:26},{name:"xyz",age:23},{name:"pqr",age:10}],
newVal = arr.map((el) => Object.assign({}, el, el.age > 25 ? {gender: "male"} : {}));
console.log("New Val:", newVal);
.as-console-wrapper { max-height: 100% !important; top: 0; }

You get a new array with map. Inside, you need to take either an copy of the object with a new property or the original object.
let array = [{ name: "abc", age: 26 }, { name: "xyz", age: 23 }, { name: "pqr", age: 10 }],
result = array.map(object => object.age > 25
? { ... object, gender: 'male' }
: object
);
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

How to create a sub-associative object from a list of array keys in JavaScript?

I have an object from user input. The keys to that object are separated by commas, and I just want to separate those keys and make the keys of the object.
The key_array below is dynamic from user input, generates a different array each time, below I give you an example.
I have shown the object in my code which you can see below. you can also see the output by running that code.
var main_array = {};
var key_array = {
'user,name' : 'user name',
'user,email' : 'Email address',
'order,id' : 123456,
'order,qty' : 2,
'order,total' : 300,
'order,product,0,name' : "product1",
'order,product,0,qty' : 1,
'order,product,0,price' : 100,
'order,product,1,name' : "product2",
'order,product,1,qty' : 1,
'order,product,1,price' : 200,
};
for (keys in key_array){
var value = key_array[keys];
// What do I do here to get the output I want?
main_array['[' + keys.split(",").join('][')+ ']'] = value;
}
console.log(main_array);
Running the code above will give you the following output which is incorrect. And the output I don't want.
{
[order][id]: 123456,
[order][product][0][name]: "product1",
[order][product][0][price]: 100,
[order][product][0][qty]: 1,
[order][product][1][name]: "product2",
[order][product][1][price]: 200,
[order][product][1][qty]: 1,
[order][qty]: 2,
[order][total]: 300,
[user][email]: "Email address",
[user][name]: "user name"
}
I want an output like JSON below, so please tell me how to do it.
{
"user":{
"email" : "Email address",
"name" : "user name"
},
"order":{
"id" : 123456,
"qty" : 2,
"total" : 300,
"product":[
{
"name" : "product1",
"price" : 100,
"qty" : 1
},{
"name" : "product2",
"price" : 200,
"qty" : 1
}
]
}
}
Note: Please do not use eval, as using eval in this way is terribly unreliable, bad work and unsafe. Because I get all my data from user input, the likelihood of abuse can increase.

Use Object.entries to go over key and values of object.
Split the key by , separator and then build the object.
While building object, make sure to merge the keys and values using mergeTo method.
Then convert the objects which has the numerical keys then convert to object using convertObjsToArray method.
var key_array = {
"user,name": "user name",
"user,email": "Email address",
"order,id": 123456,
"order,qty": 2,
"order,total": 300,
"order,product,0,name": "product1",
"order,product,0,qty": 1,
"order,product,0,price": 100,
"order,product,1,name": "product2",
"order,product,1,qty": 1,
"order,product,1,price": 200
};
const mergeTo = (target, obj) => {
Object.entries(obj).forEach(([key, value]) => {
if (typeof value === "object" && !Array.isArray(value)) {
if (!target[key]) {
target[key] = {};
}
mergeTo(target[key], obj[key]);
} else {
target[key] = value;
}
});
};
const convertObjsToArray = obj => {
Object.entries(obj).forEach(([key, value]) => {
if (typeof value === "object") {
if (Object.keys(value).every(num => Number.isInteger(Number(num)))) {
obj[key] = Object.values(value);
} else {
convertObjsToArray(obj[key]);
}
}
});
};
const res = {};
Object.entries(key_array).map(([key, value]) => {
const keys = key.split(",");
let curr = { [keys.pop()]: value };
while (keys.length > 0) {
curr = { [keys.pop()]: curr };
}
mergeTo(res, curr);
});
convertObjsToArray(res);
console.log(res);

You can create the objects and keys required from the string dynamically, take each key and split it to an array using split(','). Using each item in the array create the structure required. Assuming if a key is a number, then it's parent must be an array.
Object.keys(key_array).forEach(key => {
const path = key.split(',');
let current = main_array;
for (let i = 0; i < path.length - 1; i++) {
if (!current[path[i]]) {
current[path[i]] = path[i + 1] && !isNaN(path[i + 1]) ? [] : {};
}
current = current[path[i]];
}
current[path.pop()] = key_array[key];
});
console.log(main_array); // Desired result

Perform .join on a complex object with array of object dynamically

I have a complex js object, that contains arrays of an object. The problem is some of the main object properties' arrays can have a different property.
var foo = {};
foo.prop1 = [
{name:"test", skill:1},
{name:"test2", skill:2},
];
foo.prop2 = [
{address:"Earth",distance:1},
{address:"Mars", distance:2}
]
My aim is to just replace the main object property value with the joined values for retrieval.
This is what I have right now.
if(Object.keys(foo).length){
Object.keys(foo).forEach(key => {
var x = foo[key];
if(key === "address") {
foo[key] = x.map(function(elem){return elem.address;}).join(";");
} else {
foo[key] = x.map(function(elem){return elem.name;}).join(";");
}
});
}
How can I make it dynamic so that I don't need to use the if statement? I just want to join all the first property of the inner obj.
Result:
foo new values would be:
foo.prop1 = test;test2
foo.prop2 = Earth;Mars
I got it. I just want to join the first property of the sub object.
I replaced the if with this
foo[key] = x.map(function(elem){return elem[Object.keys(elem)[0]]; }).join(";");

I guess you are trying to choose the value with string type
var foo = {};
foo.prop1 = [{
name: "test",
skill: 1
},
{
name: "test2",
skill: 2
},
];
foo.prop2 = [{
address: "Earth",
distance: 1
},
{
address: "Mars",
distance: 2
}
]
function formulate() {
const result = {};
(Object.keys(foo) || []).forEach(function(k) {
result[k] = foo[k].map(function(val) {
str_key = Object.keys(val).filter(function(val_k) {
return typeof val[val_k] === "string";
});
return str_key.map(function(s) {
return val[s];
});
}).join(";");
});
return result;
}
result = formulate()
console.log(result);

I hope, this will work for you
var foo = {};
foo.prop1 = [
{name:"test", skill:1},
{name:"test2", skill:2},
];
foo.prop2 = [
{address:"Earth",distance:1},
{address:"Mars", distance:2}
]
Object.keys(foo).forEach(key => {
foo[key]=foo[key].map(val => { return Object.entries(val)[0][1] } ).toString().split(",").join(";")
});
console.log(foo)

Nested object: Update all attributes with same names

I have a quit complex object with multiple nested objects.
This object i want to copy and update all id attributes.
So this:
{
id: 1,
name: "A",
car: {
id: 2,
vendor: "xy"
}
..
}
should become this:
{
id: 6,
name: "A",
car: {
id: 7,
vendor: "xy"
}
..
}
Is there a way to this in a short and generic way with JavaScript (TypeScript)?
Update:
What I did so far:
const a = new MyClass();
a.id = uuid();
a.name = "A"
a.car = new Car();
a.car.id = uuid();
a.car.vendor = "xy"
//copy a
const b = JSON.parse(JSON.stringify(a));
All I want to do is increase all ids in b by 5.

You can loop through all the items in b and do two things. If it's an id property, change it (add 5). If it's an object, loop through and check both the same conditions (recursive function). Here's how you could do it:
function checkObject(obj) {
Object.keys(obj).forEach(function(prop) {
if (typeof obj[prop] == "object" && prop !== null) {
checkObject(obj[prop]);
}
else if (prop == "id") {
obj[prop] += 5;
}
})
}
Then you'd call it like so:
function checkObject(obj) {
Object.keys(obj).forEach(function(prop) {
if (typeof obj[prop] == "object" && prop !== null) {
checkObject(obj[prop]);
}
else if (prop == "id") {
obj[prop] += 5;
}
})
}
var b = {
id: 1,
name: "A",
car: {
id: 2,
vendor: "xy"
}
}
checkObject(b);
console.log(b);

Here is a function that clones the original object into a new one where each id property receives a new value generated by a given uuid function:
function assignId(data, uuid) {
return Object(data) !== data ? data
: Object.assign({}, ...Object.entries(data).map( ([k, v]) =>
({ [k]: k === "id" ? uuid() : assignId(v, uuid) })
));
}
// Example use:
function uuid() {
return uuid.next = (uuid.next || 1000) + 1;
}
const a = { id: 1, name: "A", car: { id: 2, vendor: "xy" } };
const b = assignId(a, uuid);
console.log(b);