javascript - 在javascript中向对象数组添加一个键

Question

我正在尝试将键“greeting”添加到对象数组。我的代码按预期添加了 key ，但唯一的问题是，当我控制日志时，它在底部添加了另一个数组。

function greetDevelopers(list) {

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


console.log(list);


};

返回以下内容

[ { firstName: 'Sofia',
    lastName: 'I.',
    country: 'Argentina',
    continent: 'Americas',
    age: 35,
    language: 'Java',
    greeting: 'Hi Sofia, what do you like most about Java?' },
  { firstName: 'Lukas',
    lastName: 'X.',
    country: 'Croatia',
    continent: 'Europe',
    age: 35,
    language: 'Python',
    greeting: 'Hi Lukas, what do you like most about Python?' },
  { firstName: 'Madison',
    lastName: 'U.',
    country: 'United States',
    continent: 'Americas',
    age: 32,
    language: 'Ruby',
    greeting: 'Hi Madison, what do you like most about Ruby?' },
  greeting: [ 'Hi Sofia, what do you like most about Java?',
    'Hi Lukas, what do you like most about Python?',
    'Hi Madison, what do you like most about Ruby?' ] ]

关于如何在每个对象中保留问候语但从末尾删除它的任何建议。将不胜感激。

谢谢

Answer 1

您不应该分配给 list.greeting - 它将结果分配给 array(您在数组末尾看到的新属性 - arrays不应该有这样的属性，只有元素)。你想要的只是副作用(不是新数组)，所以你应该使用 forEach 而不是 map (并且不要将结果分配给任何东西 - 只需记录数组):

const input = [ { firstName: 'Sofia',
    lastName: 'I.',
    country: 'Argentina',
    continent: 'Americas',
    age: 35,
    language: 'Java',
  }, { firstName: 'Lukas',
    lastName: 'X.',
    country: 'Croatia',
    continent: 'Europe',
    age: 35,
    language: 'Python',},
  { firstName: 'Madison',
    lastName: 'U.',
    country: 'United States',
    continent: 'Americas',
    age: 32,
    language: 'Ruby',
}];

function greetDevelopers(list) {
  list.forEach((item) => {
    item.greeting = `Hi ${item.firstName}, what do you like most about ${item.language}?`;
  });
  console.log(list);
}
greetDevelopers(input);