Question

我想创建一个由名称组成的字符串数组

function namesOnly(arr) {

}
namesOnly([
  {
    name: "Angelina Jolie",
    age: 80
  },
  {
    name: "Eric Jones",
    age: 2
  },
  {
    name: "Paris Hilton",
    age: 5
  },
  {
    name: "Kayne West",
    age: 16
  },
  {
    name: "Bob Ziroll",
    age: 100
  }
])
// expect: ["Angelina Jolie", "Eric Jones", "Paris Hilton", "Kayne West", "Bob Ziroll"]

所以希望！

Answer 1

尝试使用install them on server

class Course < ApplicationRecord belongs_to :super_course, inverse_of: :courses after_update :destroy_empty_super_course ... private def destroy_empty_super_course id = super_course_id_changed? ? super_course_id_was : super_course_id super_course = SuperCourse.find(id) super_course.destroy if super_course.courses.empty? end end方法创建一个新数组，其结果是在调用数组中的每个元素上调用提供的函数。

rspec

尽管我认为context "when super_course is updated" do let(:super_course) { create(:super_course, courses: []) } let(:course) { create(:course, super_course: super_course) } let(:new_super_course) { create(:super_course, courses: []) } let(:new_course) { create(:course, semester: course.semester, subject: course.subject, super_course: new_super_course) } subject { course.update!(super_course: new_super_course) } it "should remove old super_course" do expect { subject }.to change(SuperCourse, :count).by(-1) end end更适合这里，但您也可以使用map()循环：

function namesOnly(arr) {
  return arr.map(i => i.name);
}
var res = namesOnly([
  {
    name: "Angelina Jolie",
    age: 80
  },
  {
    name: "Eric Jones",
    age: 2
  },
  {
    name: "Paris Hilton",
    age: 5
  },
  {
    name: "Kayne West",
    age: 16
  },
  {
    name: "Bob Ziroll",
    age: 100
  }
])
console.log(res);

Answer 2

您可以使用forEach并推动创建结果

@model IEnumerable<MvcProject.Models.EmployeeModel>;

@foreach (var item in Model)
{


}

 function namesOnly(arr) {
       var result = [];
       arr.forEach(c=> { result.push(c.name); });

       console.log(result);
       return result;
    }

Answer 3

您可以使用Array.map组成一个新数组。

function namesOnly(arr) {
  return arr.map(element => { return element.name; });
}

Answer 4

    function makeStrings(arr){
      let str = arr.map(function(s) {
        if(s.age >= 17) {
         return s.name + 'can go to The Matrix';
        } else if(s.age) {
          return s.name + 'is under age!';
      } 
   })
   return str;
 }

制作一个由名称组成的字符串数组

4 个答案: