291 Updating Recipe Servings at 07:34 - an incorrect formula

[hazartilirot]

Well, if we look at the provided template there are two buttons -/+, meaning the one would increase a value by 1 and the other is the other way around i.e. decrease the value by 1.

We pass in a value of "1" to updateServings(newServing). The very first action should be made is increase the total of servings. We should take a value of servings (let's say 4) and add our 1. const totalServings = newServing + state.recipe.servings; then, we should calculate the ratio. const ratio = totalServings / state.recipe.servings and only then can we change our ingredients. However, before that, we have to check if total servings is greater than 1 if so return immediately for we could decrease servings as low as below "0".

BTW fractional library is buggy. It reaches 27 (or 28) and throws an error.

[hazartilirot]

Oh, apologies, I've jumped to conclusions. The feature would work in the end. However, what's the purpose in calculating in The View I thought we need to deal with data in a Model. Why do we change principles? Well, the actions alike confuse me. We should be consistent...

export const updateServings = function(servingsAmount) {
  let totalServings = servingsAmount + state.recipe.servings;
  if (totalServings < 1) return;
  const ratio = totalServings / state.recipe.servings;
  state.recipe.ingredients.forEach(e => {
    e.quantity = e.quantity * ratio;
  });
  state.recipe.servings = totalServings;
};