Destructure an object by an array of its keys

Question

Say that we have an object like this one:

let obj = {a: "John", b: "Sarah", c: "Lara", d: "Joseph", e: "Roger"}

And an array of some of its keys:

let arr_of_keys = ["a", "d", "e"]

Is it possible to destructure the object using the predefined keys in the array, something along the lines of:

let {...arr_of_keys} = obj;

To finally end up with:

a = "John", d = "Joseph", e = "Roger"

Answer 1

You want a simple .reduce method like the one below:

var result = arr_of_keys.reduce(function(o,item){

    if(obj.hasOwnProperty(item)){
        o[item] = obj[item]; 
    }

  return o;
}, {});

Here's an example:

 let obj = {a: "John", b: "Sarah", c: "Lara", d: "Joseph", e: "Roger"} let arr_of_keys = ["a", "d", "e", "f"]; var result = arr_of_keys.reduce(function(o,item){ if(obj.hasOwnProperty(item)){ o[item] = obj[item]; } return o; }, {}); console.log(result) 

Here's a JSFiddle runnable (since the built-in one returns a 503.)

Answer 2

Here is a possible helper function for the provided issue. I added a set conversion to remove possible duplications in order save resources. Also added simple error handling in form of console error messages.

 const obj = {a: "John", b: "Sarah", c: "Lara", d: "Joseph", e: "Roger"} const arr_of_keys = ["a", "d", "e"]; const customObjectDescructurer = (arrayOfDesiredPropKeys, object) => { const setOfDesiredPropKeys = new Set(arrayOfDesiredPropKeys); const filteredObject = [...setOfDesiredPropKeys].reduce( (filteredObject, desiredPropKey) => { if(object.hasOwnProperty(desiredPropKey)){ filteredObject[desiredPropKey] = object[desiredPropKey]; } else { console.error(` The given ${desiredPropKey}, does not exist in ${object} object. `); } return filteredObject; }, {}); return filteredObject; } const desiredKeys = customObjectDescructurer(arr_of_keys, obj); console.log(desiredKeys);