CODEWITHSUNDEEP
javascriptjavascript-objects
Fellow Stranger
Fellow Stranger

Reputation: 34113

Create a new object with property-value pairs from an other object

const ingredients = {
  fruit: 'orange', liquid: 'water', vegetable: 'tomato', spices: 'curry'
};

I want to pick some of the properties from ingredients and add them to a new object - shoppingList.

Right now I'm doing it like this:

const shoppingList = {};
shoppingList.fruit = ingredients[fruit];
shoppingList.spices = ingredients[spices];

Is there any more convenient way of doing the above? I'm envisioning a function of some sort to which I can give ingredients, fruit and spices and it will return a new object with those properties and values.

Upvotes: 1

Views: 64

Answers (3)

Josh Lin
Josh Lin

Reputation: 2437

I'm not going to provide you a function, I just believe this way goes more clean

const ingredients = {
  fruit: 'orange',
  liquid: 'water',
  vegetable: 'tomato',
  spices: 'curry'
}

//ingredients, fruit and spices

const {
  fruit,
  spices
} = ingredients

const newObj = {
  fruit,
  spices
}

document.write(JSON.stringify(newObj))

Upvotes: 0

Ja Superior
Ja Superior

Reputation: 469

You could use a function which destructures it the way you like. 

function  applySpicesandFruit ({ fruit,  spices}) { 
    this.fruit = fruit; 
    this.spices = spices 
    return this;
}
applySpicesandFruit.call(shoppinglist, ingredients);

Upvotes: 0

Sagiv b.g
Sagiv b.g

Reputation: 31024

You can use reduce to generate a new object based on keys that you pass to a function.

Small running example:

const ingredients = {
  fruit: 'orange',
  liquid: 'water',
  vegetable: 'tomato',
  spices: 'curry'
};

function pick(keys, obj) {
  const newObj = keys.reduce((result, currentKey) => {
    result[currentKey] = obj[currentKey];
    return result;
  }, {});
  return newObj;
}


const myKeys = ['fruit', 'spices'];
const customObj = pick(myKeys, ingredients);
console.log(customObj);

If you want to go really crazy you can add it to the Object.prototype and invoke it directly on objects.
Note that this will add the pick method to all objects, so maybe consider adding it just to some of your objects:

const ingredients = {
  fruit: 'orange',
  liquid: 'water',
  vegetable: 'tomato',
  spices: 'curry'
};


Object.prototype.pick = function(keys){
  const newObj = keys.reduce((result, currentKey) => {
    result[currentKey] = this[currentKey];
    return result;
  }, {});
  return newObj;
}

const myKeys = ['fruit', 'spices'];
const customObj = ingredients.pick(myKeys);
console.log(customObj);

Upvotes: 1

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