I'm a bit of a JS noob and I'm currently trying to learn array functions.
When trying to refactor some of my old code I stumbled across this:
export const determineValue = (events) => {
let eligible = false
for (const event of events) {
if (event.eventType === "1") {
eligible = true
} else if (event.eventType === "2") {
eligible = false
return eligible
}
}
return eligible
}
For this case, "1" and "2" are the only possible values of event.eventType.
How can I write this compactly?
Are there any best practices to consider here?
Thanks in advance for any clarification!
A simplified solution would be
//example setup
const events = [{"eventType":"1"},{"eventType":"2"}];
// Solution
const eventTypes = events.map(x => x.eventType);
return eventTypes.includes("1") && !eventTypes.includes("2");
I'd go with something like this :
const determineValue = (events) => {
return events.length > 0 && !(events.every(input => input.eventType === "2"));
}
If events.length > 0 is false, the part behind the && is not executed, and the function immediately returns false.
Otherwise it checks if every item in events has a value "2" for its property eventType. It returns false if the check succeeds and true if it fails, due to the ! in front of it.
const events0 =[];
const events1 =[{eventType: "1"}, {eventType: "2"}, {eventType: "1"}];
const events2 =[{eventType: "2"}, {eventType: "2"}, {eventType: "2"}];
const determineValue = (events) => {
return events.length > 0 && !(events.every(input => input.eventType === "2"));
}
console.log(determineValue(events0));
console.log(determineValue(events1));
console.log(determineValue(events2));Since the eligble events are type 1 - all you need to do is filter the events array for those and then return the length of the filtered array.
const events =[{eventType: 1},{eventType: 1},{eventType: 2},{eventType: 2},{eventType: 1},{eventType: 1}];
const determineValue = (events) => {
return events.filter(x => x.eventType === 1).length
}
;
console.log(determineValue(events)); // gives 4 events are type 1
console.log(events.length); // gives 6 events in totalTo enhance it and you can also pass in the type that you want to count (in case you want to count the ineligible events instead)
const events =[{eventType: 1},{eventType: 1},{eventType: 2},{eventType: 2},{eventType: 1},{eventType: 1}];
const determineValue = (events, value) => {
return events.filter(x => x.eventType === value).length
}
;
console.log(determineValue(events, 1)); // gives 4 events are type 1
console.log(determineValue(events, 2)); //gives 2 events are type 2
console.log(events.length); // gives 6 events in total