In this article lets discuss how the delete operator in javascript can be your rescuer. I'm jotting down my learning and working experience, so that others may found useful.

Recently I came up with a scenario where there is an array of objects with the different fields of value, and I want to remove the unwanted fields in the object and return it as an object.

Example: Array of objects with different fields.

      rewards = [
        {
            _id: "5d6fcdf63eb318a9d6981f35",
            type: "welcome_offer",
            discount: 15,
            status: true, 
            validity: "05-09-2020"
        },
        {
           _id:"5d779b833eb318a9d6f60528",
           type: "extend_subscription",
           duration: 3,
           status: true,
           validity: "05-09-2020"
        },
        {
            _id: "5d7b700b3eb318a9d6227637",
            type: "unlock_course",
            eligiblePlans: [ "js-combo", "react-combo"],
            status: true,
            validity: "05-09-2020"
        }
    ]

How the actual outcome should be?

    rewards: {
        "WELCOME_OFFER": {
            discount: 15,
            validity: "05-09-2020"
        },
        "EXTEND_SUBSCRIPTION": {
            duration: 3,
            validity: "05-09-2020"
        },
        "UNLOCK_COURSE": {
            eligiblePlans: [ "js-combo", "react-combo"],
            validity: "05-09-2020"
        }
    }

So how can bring the above array to this format?

1. Need to convert the array to object. So we can use the reduce function in javascript to convert to a single object. Okay!
2. To capitalise the type, we can just use toUpperCase() function. Okay, that also fine.

How can we remove the unwanted fields in the object? 🤔 There comes the delete operator to rescue me.

The JavaScript delete operator removes a property from an object; if no more references to the same property are held, it is eventually released automatically.

Syntax

delete object.property
delete object['property'] 

Okay, its time to put all the knowledge into coding.

    const eligible_rewards = rewards.reduce( ( acc, val) => {
             const type    = val.type.toUpperCase();
            const details  = {
                        [type]: {
                        ...val
                }
            }
            delete details[type].type;
            delete details[type].status;
            delete details[type]._id;
            return {...acc, ...details}
        },{})

Checkout this snippet in JSfiddle

I'm sure there are other ways to solve the problem. Share your solution in the comment section below. I hope you find this useful. If you find useful keep supporting me. For doubts, suggestions and feedback kindly contact me at @code_rams

Originally published by Rams Codes on Dev.