Filtering an array using reduce

Basically, I'd start w/ writing the test for a single value itself

function test(key, value) {
  const ignore = local.includes(key)
  return !ignore && value
}

Once you have that, there are many ways to run it on your entire object. And I'm not sure .reduce is the best way to go for this. I'd suggest going for .find

const activityLoading = {
  topicsForClassCourse: true,
  b: false,
  c: false,
  d: true,
  e: false
}
const local = [ "topicsForClassCourse", "e" ]

const result = Object.entries(activityLoading).find(([key, value]) => {
  const ignore = local.includes(key)
  return !ignore && value
})
console.log(result) // ['d', true]

const foundSomething = !!result
console.log(foundSomething) // true

And if you find it cumbersome to deal with ['d', true] being returned, using .some instead of .find will return a boolean instead of the value that matched the test.

But if you really want to, .reduce could do the job too, just be careful with 2 things:

• how you initialize it (second argument). It should start at false because initially you assume no value matches.
• and how you accumulate (return). It should be return accumulator || current so that any true current will make the whole result true.

const activityLoading = {
  topicsForClassCourse: true,
  b: false,
  c: false,
  d: true,
  e: false
}
const local = [ "topicsForClassCourse", "e" ]

const result = Object.entries(activityLoading).reduce((accu, [key, value]) => {
  const ignore = local.includes(key)
  const test = !ignore && value
  return accu || test
}, false)

console.log(result) // true

You should try some more simple jobs using reduce function to take it in hand. Now for your issue you can try this one:

    const loadingSome = () => {
      const local = [ "topicsForClassCourse", "timetableForClass" ];
      const entries = Object.entries(activityLoading)
      
      const reducer = (acc, current) => {
        if(local.includes(current[0])) {
          return acc
        }
        return current[1] || acc;
      }
      
      const result = entries.reduce(reducer, false)
      console.log(result)
    }

As you see you forgot to take the acc into account. I have not try out the above code but it should work. If didn't let me know.

How about first filter the object to filter out the local array keys using filter and then use some to check any key is true/false.

const activityLoading = {
  topicsForClassCourse: true,
  b: false,
  c: false,
  d: true,
  e: false
};
const local = ["topicsForClassCourse", "e"];
let result = Object.entries(activityLoading)
  .filter(([key, value]) => !local.includes(key))
  .some(([key, value]) => value);
console.log(result);

or you can use only some array helper

const activityLoading = {
  topicsForClassCourse: true,
  b: false,
  c: false,
  d: true,
  e: false
};
const local = ["topicsForClassCourse", "e"];
let result = Object.entries(activityLoading)
  .some(([key, value]) => !local.includes(key) && value)
console.log(result);