Your result array should be array of objects, to do so

const results = [{
    0: { id: 1, name: 'Leo' },
    2: { id: 2, name: 'Max' }
}]


const age = [{ id: 1, name: '14' }, { id: 2, name: '15' }]

const newArr= []

//looping overelements of result to make a new array of objects
results.forEach((e) => {
    for (let key in e) {
        newArr.push(e[key])
    }
})
console.log(newArr);

const ages = [
    { id: 1, age: '14' },
    { id: 2, age: '15' }
]

// finding the equalIds by looping over on both array and assigned a new age property in new array with the help .map
let answer = []
for (let i = 0; i < ages.length; i++) {
    answer = newArr.map((elem) => {
        if (ages[i].id === elem.id) {
            elem.age = ages[i].age
        }
        return elem
    })
}

console.log(answer);

You can use the find method (documentation here) to get the object you want and then updating the object.

Take care because the method will return null if there is no object corresponding to the parameters

So in your case you can use the for each method on one of the array (or any for loop you want like for i or for in) and update all value using find with the other array

It can be seen like

For each element on the age array, look for the element that match the id in the second array and add a property based on the value of this element

Example

const ages = [
    {id: 1, age: '14'},
    {id: 2,age: '15'}
  ]

const results = [
    {id: 1,name: 'Leo'},
    {id: 2,name: 'Max'}
  ]


//using foreach

ages.forEach((age) => {
  const resultAssociated = results.find(result => result.id === age.id)
  if (resultAssociated !== null) {
    age.name = resultAssociated.name
  }
})

console.log(ages)

Use a map function. It works same like foreach but will help you to return a value at the end.

Go with the following code, you'll achieve what you need:

let test = [{id:1,name:'n1'}, {id:2,name:'n2'}];
let ages = [{id:1,age:12},{id:2,age:13}];

Imagine test and ages to be the default variables you're getting with the following values. For you to combine both and merge them into one array of objects you need to apply map and find functions.

result = test.map(ele => {
    let ageObject = ages.find(e => e.id === ele.id);    // #1
    return {...ele, ...ageObject};    // #2
});
console.log(result);   // array of objects with test and ages values merged

#1 .find() in this line works as a search function, it searches for the object over the given array of objects taking the condition given inside as the base. It returns the first found object with the matching condition in the given array and returns it.

#2 the "...ele" syntax is called the 'spread operator' syntax and it will spread all the elements inside the given object. {...ele} is equal to {id:1,name:'n1'}. This syntax helps in forming an object with the given elements while removing duplicates if any.

You can go with the traditional for loop inside for loop approach and compare each and every element manually and do the merging of objects but trying it this way will let you leverage the ES6 features.