缩短 if else 语句

Question

How can I shorten that if else statement?

const isPathPointAvailable = (requiredItems?: ModelTypes['Item'][], oneOfItems?: ModelTypes['Item'][]) => {
    if(requiredItems && requiredItems.length > 0){
        return userHaveMultipleRequiredItems(requiredItems);
    }
    if(oneOfItems && oneOfItems.length > 0){
        return userHaveRequiredItem(oneOfItems);
    }
    return true

I tried this but it always return true

const isPathPointAvailable = (requiredItems?: ModelTypes['Item'][], oneOfItems?: ModelTypes['Item'][]) => {
    requiredItems && requiredItems.length > 0 && userHaveMultipleRequiredItems(requiredItems);
    oneOfItems && oneOfItems.length > 0 && userHaveRequiredItem(oneOfItems);
    return true
};

Answer 1

Use the optional chaining operator ?. to return the falsy undefined if the arrays are not defined. length === 0 is also falsy.

const isPathPointAvailable = (requiredItems?: ModelTypes['Item'][], oneOfItems?: ModelTypes['Item'][]) => {
    if(requiredItems?.length) return userHaveMultipleRequiredItems(requiredItems);
    if(oneOfItems?.length) return userHaveRequiredItem(oneOfItems);
    return true

You were on the right track with your second attempt, but it is missing the return statements in the shortened ifs.

Answer 2

You could also just use a simple lambda to refactor those two longer checks with something like:

let hasElements = (arr) => arr && arr.length > 0;

const isPathPointAvailable = (requiredItems?: ModelTypes['Item'][], oneOfItems?: ModelTypes['Item'][]) => {
  if( hasElements(requiredItems) ) return userHaveMultipleRequiredItems(requiredItems);
  
  if( hasElements(oneOfItems) ) return userHaveRequiredItem(oneOfItems);
  
  return true
}