Hi guys I have this scenario:
const data = [
{
"name": "Hebert",
"timestamp": 1640371815, // 15:50:15
},{
"name": "Brien",
"timestamp": 1640373855, // 16:24:15
},{
"name": "Hebert",
"timestamp": 1640363601 // 13:33:21
},{
"name": "Mary",
"timestamp": 1640356701 // 11:38:21
},{
"name": "Mary",
"timestamp": 1640356521 // 11:35:21
},{
"name": "Mary",
"timestamp": 1640356401 // 11:33:21
}
];
I need to get lasted one from duplicates by timestamp:
// expected result
[
{
"name": "Hebert",
"timestamp": 1640371815 // 15:50:15 newest one
},{
"name": "Brien",
"timestamp": 1640373855 // 16:24:15 unique
},{
"name": "Mary",
"timestamp": 1640356701 // 11:38:21 newest
}
];
I try this:
data.sort((a,b) => a.name.localeCompare(b.name))
.filter((chat, index, self) => self.findIndex( c => c.name == chat.name ) == index )
output duplicated removed but no considering newest timestamp between each duplicates
Rather than sorting and using filter you can iterate the array just once storing items in a Map or object using the names as keys and then just update the lowest timestamp as you loop through each item.
Then finally convert the object values back to array
const items = new Map()
data.forEach(({name,timestamp}) => {
const o = items.get(name);
if(o){
timestamp < o.timestamp && o.timestamp = timestamp;
} else {
items.set(name, {name, timestamp});
}
});
const res = [...items.values()]
console.log(res)<script>
const data = [
{
"name": "Hebert",
"timestamp": 1640371815, // 15:50:15
},{
"name": "Brien",
"timestamp": 1640373855, // 16:24:15
},{
"name": "Hebert",
"timestamp": 1640363601 // 13:33:21
},{
"name": "Mary",
"timestamp": 1640356701 // 11:38:21
},{
"name": "Mary",
"timestamp": 1640356521 // 11:35:21
},{
"name": "Mary",
"timestamp": 1640356401 // 11:33:21
}
];
</script>const data = [
{
"name": "Hebert",
"timestamp": 1640371815, // 15:50:15
},{
"name": "Brien",
"timestamp": 1640373855, // 16:24:15
},{
"name": "Hebert",
"timestamp": 1640363601 // 13:33:21
},{
"name": "Mary",
"timestamp": 1640356701 // 11:38:21
},{
"name": "Mary",
"timestamp": 1640356521 // 11:35:21
},{
"name": "Mary",
"timestamp": 1640356401 // 11:33:21
}
];
const seen = {};
const dataModified = [];
data.forEach((elem) => {
const index = seen[elem.name];
if(index == undefined){
dataModified.push(elem);
seen[elem.name] = dataModified.length - 1;
} else if(dataModified[index].timestamp < elem.timestamp){
dataModified.splice(index, 1, elem);
}
});
console.log(dataModified);data.sort((a,b) => a.name.localeCompare(b.name))
.filter((chat, index, self) => self.findIndex(c => c.name === chat.name && c.timestamp > chat.timestamp)<0)
The idea is that findIndex would only return the index when there exists another duplicate with greater timestamp, else it'd return -1.