javascript - forEach 返回未定义

Question

我希望 foreach() 循环遍历映射数组并检查类型值是否匹配。如果没有返回else语句。

函数

function checkCars(carData) {
        const cars = carData.models;

        models.forEach(model => {
            if (model.type === 'Toyota' || model.type === 'Hyundai') {
                return "Type A";
            } else {
                return "Type B";
            }
        });
    }

数据库

"models": [
  {type: "Toyota"}
  {type: "Hyundai"}
  {type: "Audi"}
  {type: "VW"}
]

Answer 1

Array.prototype.forEach()的返回值是未定义，您无法从forEach()显式返回任何内容。

您可以尝试使用 Array.prototype.map()相反:

The map() method creates a new array populated with the results of calling a provided function on every element in the calling array.

function checkCars(carData) {
  const cars = carData.models;

  return models.map(model => {
    if (model.type === 'Toyota' || model.type === 'Hyundai') {
      return "Type A";
    } else {
      return "Type B";
    }
  });
}