I have an array of strings:
var array = ['bob', 'charlie', 'bob', 'bob'];
that I want to remove duplicates from, and then I'd like to convert it to an array of objects whilst adding a duplicate count property.
This is what I want to achieve:
var filteredData = [{ name: 'bob', count: 3}, { name: 'charlie', count: 1}];
How can I do that?
Ecmascript5 solution using Array.prototype.reduce() function:
var arr = ['bob', 'charlie', 'bob', 'bob'],
counts = arr.reduce(function(r,s){
(!r[s])? r[s] = {name: s, count: 1} : r[s]['count']+=1;
return r;
}, {}),
result = Object.keys(counts).map(function(k){ return counts[k]; });
console.log(result);Ecmascript6 version (with Object.values() function):
var arr = ['bob', 'charlie', 'bob', 'bob'],
result = Object.values(arr.reduce((r,s) => {
(!r[s])? r[s] = {name: s, count: 1} : r[s]['count']+=1;
return r;
}, {}));
console.log(result);Using Map with Array#reduce:
const array = ['bob', 'charlie', 'bob', 'bob'];
const result = [...array.reduce((map, name) => {
const current = map.get(name) || { name, count: 0 };
current.count++;
return map.set(name, current);
}, new Map()).values()];
console.log(result);Here is some straightforward usage of Array.prototype.reduce:
const data = ['bob', 'charlie', 'bob', 'bob']
const result = data.reduce(function(prev, curr) {
const index = prev.findIndex(el => el.name === curr)
if (index !== -1) {
prev[index].count += 1
} else {
prev.push({ name: curr, count: 1 })
}
return prev
}, [])
console.log(result)