I'm looking for a method to pick random objects from an array of objects where a specific property has a unique value.
Example:
const array = [
{
name:'foo',
message: 'hello'
},
{
name:'foo',
message: 'world'
},
{
name:'bar',
message: 'hello'
},
{
name:'bar',
message: 'world'
},
]
function theMagicMethod(elementsCount, specificUniqueProperty){
// ...
};
console.log(theMagicMethod(2, name));
// Expected output: [{name:'foo', message:'hello'},{name:'bar', message:'hello'}]
// or [{name:'foo', message:'hello'},{name:'bar', message:'world'}]
// etc...
// BUT NEVER WANT: [{name:'foo', message:'hello'},{name:'foo', message:'world'}]
I've tried to use do ... while or while ... but it always crash when I conditionally add an element to my result array.:
let items = [];
do{
let item = array[Math.floor(Math.random()*array.length)];
let found = false;
for(var i = 0; i < vendors.length; i++) {
if (vendors[i].Name == 'Magenic') {
found = true;
break;
}
}
if(!found){
items.push(item)
}
} while (items.length < 3)
Shuffle the objects, use a set to filter unique values, return the first N...
// fy shuffle, thanks to https://stackoverflow.com/a/2450976/294949
function shuffle(array) {
let currentIndex = array.length, randomIndex;
while (currentIndex != 0) {
randomIndex = Math.floor(Math.random() * currentIndex);
currentIndex--;
[array[currentIndex], array[randomIndex]] = [
array[randomIndex], array[currentIndex]];
}
return array;
}
function theMagicMethod(elementsCount, specificUniqueProperty) {
let shuffled = shuffle(array.slice());
let uniqueValues = new Set()
let unique = shuffled.filter(el => {
const value = el[specificUniqueProperty];
const keep = !uniqueValues.has(value)
uniqueValues.add(value);
return keep;
})
return unique.slice(0, elementsCount);
}