javascript - 根据属性返回对象值

Question

我有一个包含各种动物的对象:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}]

我只想返回猫类动物的名称。我正在努力这样做。这是我的尝试:

var cats = []
function onlyCats(array) {
  if (toonimals.animal === 'cat') {
    cats.push(toonimals.name)
  }
  return cats
}
console.log(onlyCats(toonimals));

目前，它仅返回空数组，因此 .push() 方法由于某种原因不起作用。

提前谢谢您。

Answer 1

您必须循环数组到 filter()这个动物。然后使用map()修改数组以返回名称:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}];

function onlyCats(array) {
  return array.filter(a => a.animal === 'cat').map(a => a.name);
}
console.log(onlyCats(toonimals));

在forEach()的帮助下以您的方式:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}];

var cats = []
function onlyCats(array) {
  array.forEach(function(animal){
    if (animal.animal === 'cat') {
      cats.push(animal.name)
    }
  });
  return cats;
}
console.log(onlyCats(toonimals));