I want to find an item and the index of this item inside array and store this in 2 separate variables. Quite new to programming but struggling to solve the problem. I tried destructing but it is not working
const [{item:item,index:index}] = notification.pendingQueue.forEach((item,index)=>
{
if(item.taskId.toString() === req.params.taskId)
return [{item, index}];
})
Tried this as well
const data = notification.pendingQueue.forEach((item,index)=>
{
if(item.taskId.toString() === req.params.taskId)
return ({'item': item, 'index': index})
})
console.log("item", data.item );
I'm getting this error
undefined is not iterable (cannot read property Symbol(Symbol.iterator)) TypeError: undefined is not iterable (cannot read property Symbol(Symbol.iterator))
------ Edit -------------
As suggested by the community member, I tried .map method but now the issue is I get results like this if the 2nd element matches the condition.
[undefined, {item,index}, undefined]
so doing object destructing is becoming a problem. I want the final array to contain just the matching object and remove all undefined values.
const [{ item, index }] = notification.pendingQueue.map((item,index)=>
{
if(item.taskId.toString() === req.params.taskId)
return { item, index };
}) ;
Array.forEach do not return any value. You should use map instead :
const [{ item, index }] = notification.pendingQueue.map((item,index)=>
{
if(item.taskId.toString() === req.params.taskId)
return { item, index };
}) ;
Note that item and index may be undefined if your condition is not fulfilled.
To remove undefined you can chain map result with Array.filter :
const [{ item, index }] = notification.pendingQueue.map((item,index)=>
{
if(item.taskId.toString() === req.params.taskId)
return { item, index };
}).filter(elem => elem !== undefined) ;
You can return multiple values from a function by wrapping them in an iterable. See this link on destructuring assignment.
function coordinates (country = null) {
if (!country) return [-1, -1];
// ...
let lat = "19.9823";
let lon = "0.9039";
return [lat, lon];
}
const [a, b] = coordinates("London, UK");
Or
function coordinates (country = null) {
if (!country) return {-1, -1};
// ...
let lat = "19.9823";
let lon = "0.9039";
return {lat, lon};
}
const {lat, lon} = coordinates("Tokyo, JP");