how to merge two objects into one in javascript

                                    // reusable function to merge two or more objects
function mergeObj(...arr){
  return arr.reduce((acc, val) => {    
    return { ...acc, ...val  };
  }, {});
}

// test below

const human = { name: "John", age: 37 };

const traits = { age: 29, hobby: "Programming computers" };

const attribute = { age: 40, nationality: "Belgian" };

const person = mergeObj(human, traits, attribute);
console.log(person);
// { name: "John", age: 40, hobby: "Programming computers", nationality: "Belgian" }

                                    let obj1 = { foo: 'bar', x: 42 };
let obj2 = { foo: 'baz', y: 13 };

let clonedObj = { ...obj1 };
// Object { foo: "bar", x: 42 }

let mergedObj = { ...obj1, ...obj2 };
// Object { foo: "baz", x: 42, y: 13 }

                                    const response = {
  lat: -51.3303,
  lng: 0.39440
}

const item = {
  id: 'qwenhee-9763ae-lenfya',
  address: '14-22 Elder St, London, E1 6BT, UK'
}

const newItem = { ...item, location: response }; // or { ...response } if you want to clone response as well

console.log(newItem );

                                    // Exporting individual features
export let name1, name2, …, nameN; // also var, const
export let name1 = …, name2 = …, …, nameN; // also var, const
export function functionName(){...}
export class ClassName {...}

// Export list
export { name1, name2, …, nameN };

// Renaming exports
export { variable1 as name1, variable2 as name2, …, nameN };

// Exporting destructured assignments with renaming
export const { name1, name2: bar } = o;

// Default exports
export default expression;
export default function (…) { … } // also class, function*
export default function name1(…) { … } // also class, function*
export { name1 as default, … };

// Aggregating modules
export * from …; // does not set the default export
export * as name1 from …;
export { name1, name2, …, nameN } from …;
export { import1 as name1, import2 as name2, …, nameN } from …;
export { default } from …;

                                    const obj1 = {'a': 1, 'b': 2};
const obj2 = {'c': 3};
const obj3 = {'d': 4};

const objCombined = {...obj1, ...obj2, ...obj3};