My data:
[{
id: 1,
name: 'foo'
}, {
id: 2,
name: 'bar'
}, {
id: 1,
name: 'foo'
}
];
I want to do something like this:
[
{
name: "foo",
id: 1,
count: 2
},
{
name: "bar",
id: 2,
count: 1
}
]
Now i'm grouping the elements with groupBy by name.
Thanks for the help!
var source = [{
id: 1,
name: 'foo'
}, {
id: 2,
name: 'bar'
}, {
id: 1,
name: 'foo'
}
];
var result = _(source)
.groupBy('name')
.map(function(items, name) {
return {
name: name,
count: items.length
}
}).value();
console.log(result);<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>It's not exactly what you asked for, but here is a simple method without using lodash. Here I'm using the ID of each element, but you can use anything that uniquely identifies it.
const objArray = [{
id: 1,
name: 'foo'
}, {
id: 2,
name: 'bar'
}, {
id: 1,
name: 'foo'
}
];
const reduceAndCount = (arr) => {
const newMap = {};
arr.forEach(el => {
if (!newMap[el.id]) {
el.count = 1
return newMap[el.id] = el
}
newMap[el.id].count = newMap[el.id].count + 1
})
return Object.values(newMap)
}
const result = reduceAndCount(objArray)
console.log(result)With deference to the answer provided here which uses 'lodash', as requested in the above question, the below points are observed:
EDIT: Adding solution using lodash,
const arrayRaw = [{
id: 1,
name: 'foo'
}, {
id: 2,
name: 'bar'
}, {
id: 1,
name: 'foo'
}];
const groupBy = (col = 'name', arr = arrayRaw) => (
_(arr).groupBy(col).map(it => ({
...it[0],
count: it.length
})).value()
);
console.log(groupBy());<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/1.2.1/lodash.min.js"></script>In case, someone requires a solution without 'lodash', the below should be one possible implementation:
const arrayRaw = [{
id: 1,
name: 'foo'
}, {
id: 2,
name: 'bar'
}, {
id: 1,
name: 'foo'
}];
const groupBy = (col = 'name', arr = arrayRaw) => (
Object.entries(arr.reduce((fin, itm, idx) => ({
...fin,
[itm[col]]: (fin[itm[col]] || []).concat([idx])
}), {})).map(([k, v]) => ({
...arr[v[0]],
count: v.length
}))
);
console.log(groupBy());Approach / Explanation It is self-explanatory, however, should anyone require one - please comment and I shall add.