Javascript - Iterating through nested arrays and objects to apply filtering

Question

Javascript - Iterating through nested arrays and objects to apply filtering

I am currently trying to fetch specific arrays based on a certain criterion. I am a bit unsure about how to go about filtering the arrays, so I thought I would seek clarification here. Essentially, I have a list of courses and I want to extract all the courses where the level is equal to 1.

 let courses = [{
               math:[{id:1,level_id:1,requirement:'1 Credit'}]
               spanish:[{id:5,level_id:1,requirement:'5 Credits'}] 
               technology:[{id:3,level_id:1,requirement:'2 Credits'}]
            }];
             
            let queryCoursesForLevelWhereIDMatches = 1
            
            let returnedArrays = courses.filter()
             
             console.log(returnedArrays);

javascript arrays sorting

Answer 1

Answer №1

If you're looking to implement a solution, consider the following approach:

function CourseManager(courses = null){
  this.courses = courses;
  this.getByCategory = (category, value = null)=>{
    return this.courses[category].filter(course=>{
      let propertyExists = course.hasOwnProperty(value);
      if(value === null){
        return propertyExists;
      }
      return propertyExists && value === course[value];
    });
  }
  this.getAllCourses = (category, value = null)=>{
    const mathCourses = this.getByCategory('math', value);
    const spanishCourses = this.getByCategory('spanish', value);
    const techCourses = this.getByCategory('technology', value);
    return {math: mathCourses, spanish: spanishCourses, technology: techCourses}
  }
}
const courses = {
  math:[{id:1,level_id:1,requirement:'1 Credit'}, {id:2,level_id:2,requirement:'2 Credits'}],
  spanish:[{id:2,level_id:2,requirement:'2 Credits'}, {id:5,level_id:1,requirement:'5 Credits'}],
  technology:[{id:3,level_id:1,requirement:'2 Credits'}, {id:2,level_id:2,requirement:'2 Credits'}]
}
const cm = new CourseManager(courses);
console.log(cm.getAllCourses('level_id', 1));

Answer 2

If you're looking to implement a solution, consider the following approach:

function CourseManager(courses = null){
  this.courses = courses;
  this.getByCategory = (category, value = null)=>{
    return this.courses[category].filter(course=>{
      let propertyExists = course.hasOwnProperty(value);
      if(value === null){
        return propertyExists;
      }
      return propertyExists && value === course[value];
    });
  }
  this.getAllCourses = (category, value = null)=>{
    const mathCourses = this.getByCategory('math', value);
    const spanishCourses = this.getByCategory('spanish', value);
    const techCourses = this.getByCategory('technology', value);
    return {math: mathCourses, spanish: spanishCourses, technology: techCourses}
  }
}
const courses = {
  math:[{id:1,level_id:1,requirement:'1 Credit'}, {id:2,level_id:2,requirement:'2 Credits'}],
  spanish:[{id:2,level_id:2,requirement:'2 Credits'}, {id:5,level_id:1,requirement:'5 Credits'}],
  technology:[{id:3,level_id:1,requirement:'2 Credits'}, {id:2,level_id:2,requirement:'2 Credits'}]
}
const cm = new CourseManager(courses);
console.log(cm.getAllCourses('level_id', 1));

Answer 3

Answer №2

You have the ability to filter the entries based on their level_id values and then associate them with their respective course names.

Furthermore, I have reassigned "Spanish" to level 2 to ensure it is excluded from the results.

Important: As the object is nested within an array, you can destructure the object and then transform it into individual entries.

let courses = [{
   math       : [ { id: 1, level_id: 1, requirement: '1 Credit'  } ],
   spanish    : [ { id: 5, level_id: 2, requirement: '5 Credits' } ],
   technology : [ { id: 3, level_id: 1, requirement: '2 Credits' } ]
}];

const findCoursesWhereLevelIdEquals = ([ courses ], id) =>
  Object.entries(courses)
    .filter(([ , [ { level_id } ] ]) => level_id === id)
    .map(([ courseName ]) => courseName);

console.log(findCoursesWhereLevelIdEquals(courses, 1));

.as-console-wrapper { top: 0; max-height: 100% !important; }

Answer 4

You have the ability to filter the entries based on their level_id values and then associate them with their respective course names.

Furthermore, I have reassigned "Spanish" to level 2 to ensure it is excluded from the results.

Important: As the object is nested within an array, you can destructure the object and then transform it into individual entries.

let courses = [{
   math       : [ { id: 1, level_id: 1, requirement: '1 Credit'  } ],
   spanish    : [ { id: 5, level_id: 2, requirement: '5 Credits' } ],
   technology : [ { id: 3, level_id: 1, requirement: '2 Credits' } ]
}];

const findCoursesWhereLevelIdEquals = ([ courses ], id) =>
  Object.entries(courses)
    .filter(([ , [ { level_id } ] ]) => level_id === id)
    .map(([ courseName ]) => courseName);

console.log(findCoursesWhereLevelIdEquals(courses, 1));

.as-console-wrapper { top: 0; max-height: 100% !important; }

Javascript - Iterating through nested arrays and objects to apply filtering

Answer №1

Answer №2

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