To find the key of the object below based on a value in the arrays, we can do:
const obj = {
fruit: ['banana', 'apple', 'orange'],
veg: ['cabbage', 'carrot', 'pepper'],
drink: ['milk'],
}
const getKey = toFind => Object.keys(obj).find(key => obj[key].includes(toFind))
getKey('apple') // returns fruit
getKey('carrot') // returns veg
Similarly, if our object didn't have arrays but single values, we could do
const obj = {
starter: 'garlic bread',
main: 'cheese pizza',
drink: 'coca-cola',
}
const getKey = toFind => Object.keys(obj).find(key => obj[key] === toFind)
getKey('garlic bread') // returns starter
getKey('cheese pizza') // returns main