insert multiple object with same key-value in array based on condition in javascript

Question

I have object that has multiple values for example

let obj = {
  a: "day1",
  b: "",
  c: "day3",
  aa: 10,
  bb: 11,
  cc: 12,
}
let data = {};
let item = [];
for (let i in obj) {
  if (i === 'a') {
    data["title"] = obj.a;
    data['value'] = obj.aa;
  }
  if (i === 'b') {
    data["title"] = obj.b;
    data['value'] = obj.bb;
  }
  if (i === 'c') {
    data["title"] = obj.c;
    data['value'] = obj.cc;
  }
  item.push(data);
}
console.log(item)

but I'm getting only last day3 value in multiple times .

item [
        {title:"day3",value:12},
        {title:"day3",value:12},
{title:"day3",value:11}
        ]

I want in the following format

item [
    {title:"day1",value:10},
    {title:"day3",value:11}
    ]

please help, thanks in advance.

when you loop like that, you don't get values but keys (property names). You are comparing i === 'day2' but i will be equal to the current property name not value. You should really break down your problems and verify its parts before addressing the problem as a whole — Diego D
– Diego D, Commented Apr 8, 2022 at 11:24
Of cause the OP gets the last state since the OP always reassigns the same properties (title and value) at one and the same data object. The OP wants to use an array and push at/each time a newly created data object into it. — Peter Seliger
– Peter Seliger, Commented Apr 8, 2022 at 11:34

Peter Seliger · Accepted Answer · 2022-04-08 12:05:54Z

From the above comments ...

"Of cause the OP gets the last state since the OP always reassigns the same properties (title and value) at one and the same data object. The OP wants to use an array and push at/each time a newly created data object into it."

Peter Seliger can you give me any example of solution – omkar p

const obj = {
  a: "day1",
  b: "",
  c: "day3",
  aa: 10,
  bb: 11,
  cc: 12,
}
const items = [];

// slightly fixed OP approach.
for (const key in obj) {
  if (key === 'a') {
    items.push({
      title: obj.a,
      value: obj.aa,
    });
  }
  if (key === 'b') {
    items.push({
      title: obj.b,
      value: obj.bb,
    });
  }
  if (key === 'c') {
    items.push({
      title: obj.c,
      value: obj.cc,
    });
  }
}
console.log({ items });

// or entirely generic/configurable and maybe even more expressive ...
console.log(
  Object
    .entries(obj)
    .reduce(({ target, valueMap, result }, [key, value]) => {

      if (key in valueMap) {
        result.push({
          title: value,
          value: target[valueMap[key]],
        });
      }
      return { target, valueMap, result };
    }, {
      target: obj,
      valueMap: { a: 'aa', b: 'bb', c: 'cc' },
      result: [],

    }).result
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

Diego D · Accepted Answer · 2022-04-08 12:25:06Z

0

You should declare the data variable inside the loop because otherwise you are always changing its value at each iteration and that object is what you are adding to the item variable and its value it's always written over the previous one. If you create a new object at each iteration it will be on its own and no further iteration is going to overwrite its value.

*As it was pointed out in the comments, I added a check in your loop to skip iterations not belonging to the cases: 'a','b','c'; so that your final array won't contain empty objects.

let obj = {
  a: "day1",
  b: "",
  c: "day3",
  aa: 10,
  bb: 11,
  cc: 12,
}
let item = [];
for (let i in obj) {

  //this check decides if you want to skip this iteration
  //so that you won't have empty object appended to your result array
  //if(i!='a' && i!='b' && i!='c')
  //    continue;
  //this check was replaced by the final check later for better mantainance
  
  //this was (before) the only thing I changed
  let data = {};
  if (i === 'a') {
    data["title"] = obj.a;
    data['value'] = obj.aa;
  }
  if (i === 'b') {
    data["title"] = obj.b;
    data['value'] = obj.bb;
  }
  if (i === 'c') {
    data["title"] = obj.c;
    data['value'] = obj.cc;
  }

  let isEmpty = Object.keys(data).length === 0;
  //this will check if data is empty before pushing it to the array
  if(!isEmpty)
      item.push(data);
}
console.log(item)

edited Apr 8, 2022 at 12:25

answered Apr 8, 2022 at 11:36

Diego D

8,3592 gold badges24 silver badges39 bronze badges

3 Comments

Peter Seliger Over a year ago

@omkarp ... you might countercheck whether this solution returns the result you really want ... for every key which gets not covered by the if clauses an empty object gets pushed into item, thus for the given example one ends up with 3 additional empty objects.

Peter Seliger Over a year ago

As the code presents itself right now, one needs to update the continue guard line every time one adds/removes an if clause.

Diego D Over a year ago

yes but frankly it's really over-doing. I mean the logic of that loop has a deep dependency with the object definition and doing that check at the end controlling if the data object is empty is needed just to reduce the mantainance required in case those switch cases will be updated in any future. But yet it's not totally pointless so I added to the answer. Thanks for pointing out.

linwute · Accepted Answer · 2022-06-11 03:57:55Z

0

Array loading object needs deep copy,

// 多个对象载入 数组中，需要深拷贝，不然键指相同
let objXXX = {
    a:123,
    b:456,
    C:789
};
let arrYYY = [];
arrYYY[0] = JSON.parse(JSON.stringify(objXXX));
arrYYY[1] = JSON.parse(JSON.stringify(objXXX));


arrYYY[0].a = "123";
arrYYY[1].a = "9923";

// 0: Object { a: "123", b: 456, C: 789 }
// 1: Object { a: "9923", b: 456, C: 789 }
console.log(arrYYY);

answered Jun 11, 2022 at 3:57

linwute

1

Collectives™ on Stack Overflow

insert multiple object with same key-value in array based on condition in javascript

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related