How to Merge Objects in JavaScript

// Merge objects with the spread operator:
const aquatic     = { dove:  '🕊'  };
const aerial      = { panda: '🐼' };
const terrestrial = { fish:  '🐟' };

const animals = { ...aquatic, ...aerial, ...terrestrial };

// Results in the following output:
{
    dove: '🕊',
    panda: '🐼',
    fish: '🐟'
}

const aquatic = { dove: '🐼' };
const aerial = { dove: '🕊' };

const animals = { ...aquatic, ...aerial };

// Results in the following output:
{
    dove: '🕊'
}

const aquatic     = { dove:  '🕊'  };
const aerial      = { panda: '🐼' };
const terrestrial = { fish:  '🐟' };

// There is no limit to the amount of objects you can merge together
Object.assign(aquatic, aerial, terrestrial);

// If you want to copy everything into a brand new object,
// set the first param to an empty object:
Object.assign({}, aquatic, aerial, terrestrial);