toggle-value.js

function shallowEqual(a, b) {
  return JSON.stringify(a) === JSON.stringify(b)
}

function toggleValue(value, item) {
  let previousValue = false
  const newValue = value.reduce((values, value) => {
    if (shallowEqual(item, value)) {
      previousValue = true
      return values
    } else {
      return [...values, value]
    }
  }, [])
  if (!previousValue) {
    newValue.push(item)
  }
  return newValue
}