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

Question

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.

Shubham Khatri · Accepted Answer · 2020-05-24 10:05:16Z

1

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)

answered May 24, 2020 at 10:05

Shubham Khatri

284k58 gold badges431 silver badges411 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ashish singh · Accepted Answer · 2020-05-24 10:09:32Z

1

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)

answered May 24, 2020 at 10:09

ashish singh

6,9142 gold badges18 silver badges41 bronze badges

Comments

Ele · Accepted Answer · 2020-05-24 10:09:34Z

1

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; }

answered May 24, 2020 at 10:09

Ele

33.8k7 gold badges43 silver badges80 bronze badges

Comments

Nina Scholz · Accepted Answer · 2020-05-24 10:09:44Z

1

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; }

answered May 24, 2020 at 10:09

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Collectives™ on Stack Overflow

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

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related