I'd like to filter an array of objects. The array is a list of sport classes, and the objects are the classes.

It looks like this :

const list = [{category: "yoga", level: "beginner", duration: "15 minutes"}] 

I have to apply filter so the user can choose between category (yoga, pilates...) level (beginner, advanced..).

I need to find the intersection of the filter, meaning if "yoga" and "beginner" are selected, I'd like to return only beginner yoga classes.

User can turn true/false the variables beginnnerFilter etc.. and the variables cardio/yoga etc... So if the yoga filter is true, yogaFilter = "yoga". If false, yogaFilter = ""

Example:

function filterIntersect() {
  let filteredListCategory = [];
  let filteredListLevel = [];

  
  for(let i = 0; i < list.length; i++) {
    if (list[i].category.toLowerCase() === cardio) {
       filteredListCategory.push(list[i])
   } else if (list[i].category.toLowerCase() === yoga) {
       filteredListCategory.push(list[i])
   } else if (list[i].category.toLowerCase() === boxing) {
       filteredListCategory.push(list[i])
   } else if (list[i].category.toLowerCase() === dance) {
       filteredListCategory.push(list[i])
   } else if (list[i].category.toLowerCase() === pilates) {
       filteredListCategory.push(list[i])
   } else if (list[i].category.toLowerCase() === stretching) {
       filteredListCategory.push(list[i])
   } 
  }

  if (allFilterCategory === true) {
       filteredListCategory = [...list];
   }

  for(let k = 0; k < list.length; k++) {
    if (list[k].level.toLowerCase() === beginnerFilter) {
       filteredListLevel.push(list[k])
   } else if (list[k].level.toLowerCase() === intermediateFilter) {
       filteredListLevel.push(list[k])
   } else if (list[k].level.toLowerCase() === advancedFilter) {
       filteredListLevel.push(list[k])
   }
  } 

  if (allFilterLevel === true) {
       filteredListLevel = [...list];
   }

let finalList = filteredListCategory.filter(item=> filteredListLevel.includes(item));

return finalList.length === 0 ? list : finalList;
}

I manage to return a filtered array but it doesn't work as expected. Sometimes the filters do not apply and I have the full list instead of the filtered list. I'm not sure the for loop is appropriate here? I also tried using new Set but was not working either. Big thanks.