Swapping Keys and Values of a JSON Object in JavaScript

JavaScript objects store data as key-value pairs. Swapping keys and values creates a new object where the original values become keys and the original keys become values.

• Create a new object to store the swapped key-value pairs.
• Iterate through the original object's properties.
• Assign each value as a key and its corresponding key as the value.

Note: Object keys must be unique. If multiple properties have the same value, later values can overwrite earlier ones when the object is swapped.

Approach 1: Using a for...in Loop

In this approach, a for...in loop iterates through each property of the object. A new object is created by assigning the original value as the key and the original key as its value.

const obj = {
    Prop_1: "Val_1",
    Prop_2: "Val_2",
    Prop_3: "Val_3"
};

function swapKeysAndValues(object) {
    const result = {};

    for (const key in object) {
        if (Object.hasOwn(object, key)) {
            result[object[key]] = key;
        }
    }

    return result;
}

const swappedObject = swapKeysAndValues(obj);

console.log(swappedObject);

{ Val_1: 'Prop_1', Val_2: 'Prop_2', Val_3: 'Prop_3' }

Approach 2: Using Object.keys() and forEach()

In this approach, Object.keys() returns an array containing the object's keys. The forEach() method then iterates through these keys and creates the swapped object.

let obj = {
    "Prop_1": "Val_1",
    "Prop_2": "Val_2",
    "Prop_3": "Val_3"
};
function swapValues(o) {
    const res = {};
    Object.keys(o).forEach(key => {
        res[o[key]] = key;
    });
    return res;
}
function GFG_Fun() {
    console.log(JSON.stringify(swapValues(obj)));
}
GFG_Fun();

{"Val_1":"Prop_1","Val_2":"Prop_2","Val_3":"Prop_3"}

Approach 3: Using Object.entries() and reduce()

In this approach, Object.entries() converts the object's key-value pairs into an array. The reduce() method then creates a new object with the keys and values swapped.

const obj = {
    Prop_1: "Val_1",
    Prop_2: "Val_2",
    Prop_3: "Val_3"
};

const swappedObject = Object.entries(obj).reduce(
    (result, [key, value]) => {
        result[value] = key;
        return result;
    },
    {}
);

console.log(swappedObject);

{ Val_1: 'Prop_1', Val_2: 'Prop_2', Val_3: 'Prop_3' }

Note: Although this operation is often described as swapping keys and values of a JSON object, JSON itself is a data format. In JavaScript, the swapping operation is performed on a parsed JavaScript object.