为什么我的代码返回数组的最后一个值而不是为每个项目返回结果？

Question

You will be given an array of objects (associative arrays in PHP) representing data about developers who have signed up to attend the next coding meetup that you are organising.

Your task is to return an array where each object will have a new property 'greeting' with the following string value:

Hi < firstName here >, what do you like the most about < language here >?

For example, given the following input array:

 var list1 = [ { firstName: 'Sofia', lastName: 'I.', country: 'Argentina', continent: 'Americas', age: 35, language: 'Java' }, { firstName: 'Lukas', lastName: 'X.', country: 'Croatia', continent: 'Europe', age: 35, language: 'Python' } ]

your function should return the following array:

 [ { firstName: 'Sofia', lastName: 'I.', country: 'Argentina', continent: 'Americas', age: 35, language: 'Java', greeting: 'Hi Sofia, what do you like the most about Java?' }, { firstName: 'Lukas', lastName: 'X.', country: 'Croatia', continent: 'Europe', age: 35, language: 'Python', greeting: 'Hi Lukas, what do you like the most about Python?' }];

So far I have this:

var count = 0;

  for (var i = 0; i < list.length; i++){

  count +=1;

    list.forEach (function greet(string){

    string.Greeting = "Hi " + list[i].firstName + ",what do you like most about " + list[i].language + "?";

    });  // For each object in array, add string "greeting:" using function

  }

console.log(list);

}

This returns the greeting, but returns the last person in the array's name and language, rather than each individual separately.

Answer 1

As @TKoL says, you are wrongly mixing for and forEach. You just need to:

for (var i = 0; i < list.length; i++){
  list[i].greeting = `Hi ${list[i].firstName}, what do you like most about ${list[i].language}?`;
}

or

list.forEach(l => l.greeting = `Hi ${l.firstName}, what do you like most about ${l.language}?`);

Answer 2

Welcome to Stack Overflow.

You should use a .map() operator instead of a forEach as it can return a new array, like this:

const newList = list.map (function greet(person){
    return {greeting : "Hi " + person.firstName + ",what do you like most about " + person.language + "?", ...person};
});  
console.log(newList);

Answer 3

Here is the full code:

var count = 0;
var list = [
    {
        firstName: 'Sofia',
        lastName: 'I.',
        country: 'Argentina',
        continent: 'Americas',
        age: 35,
        language: 'Java'
    },

    {
        firstName: 'Lukas',
        lastName: 'X.',
        country: 'Croatia',
        continent: 'Europe',
        age: 35,
        language: 'Python'
    }
];

for (var i = 0; i < list.length; i++) {
    count += 1;

    list[i].Greeting =
        'Hi ' +
        list[i].firstName +
        ',what do you like most about ' +
        list[i].language +
        '?';
}

console.log(list);

Answer 4

You can simply use for of loop.

Here is the working example.

 const list1 = [ { firstName: 'Sofia', lastName: 'I.', country: 'Argentina', continent: 'Americas', age: 35, language: 'Java' }, { firstName: 'Lukas', lastName: 'X.', country: 'Croatia', continent: 'Europe', age: 35, language: 'Python' } ]; for (let person of list1){ person.greeting = `Hi ${person.firstName}, what do you like the most about ${person.language}?` } console.log(list1);

Answer 5

Make a function to add a property to an object:

function addGreeting(person) {
  return {...person, greeting: `Hi ${person.name}, what do you like most about ${person.language}?`};
}

And map your array elements to modified ones:

people = people.map(person => addGreeting(person));