How can I double loop using filter?

Question

I'm creating this function that returns only those objects (from an object array) whose property "a" value is not in another array of excluded numbers (which are actually strings)

I realized that I need a double iteration, tried to nest a filter, inside a filter but didn't succeed. I had to hardcode it using the OR operator like this:

const arr = [{a:"1"},{a:"2"},{a:"3"}]

const filtered = (arr)=>{
  const ex = ["1","2"]

  return arr.filter(e =>   !e.a.includes(ex[0] || ex[1]))
  
}
console.log(filtered(arr));

How can I loop this properly so that I don't have to use the || operator?

That's not how you use the || operator. If you need two test in two variables, it should be !e.a.includes(ex[0]) || !e.a.includes(ex[0]). Also, || should be &&. — Barmar
– Barmar, Commented Jul 20, 2021 at 15:26

Barmar · Accepted Answer · 2021-07-20 08:57:35Z

6

You don't need two loops. You have the includes backwards.

return arr.filter(e => !ex.includes(e.a))

answered Jul 20, 2021 at 8:57

Barmar

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2 Comments

Nikita Mazur Over a year ago

1. filter 2. includes - looks like 2 loops to me)

Barmar Over a year ago

The OP had multiple calls to include, so he was talking about another loop.

Nikita Mazur · Accepted Answer · 2021-07-20 08:56:03Z

4

const arr = [{a:"1"},{a:"2"},{a:"3"}]

const filtered = (arr)=>{
  const ex = ["1","2"]

  return arr.filter(e => !ex.includes(e.a))
  
}
console.log(filtered(arr));

answered Jul 20, 2021 at 8:56

Nikita Mazur

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