Hey I'm struggling and was hoping that maybe someone here could help. I'm making a web app that uses a big array of objects that looks similar to this:
var arr = [
{
prop1 : "foo",
prop2 : ["foo1", "foo2", "foo3", "foo4"],
prop3 : "foo5",
prop4 : "foo6",
},
{
prop1 : "bar",
prop2 : ["bar1", "bar2", "bar3", "bar4"],
prop3 : "bar5",
prop4 : "bar6",
},
{
prop1 : "something",
prop2 : ["something1", "something2", "something3", "something4"],
prop3 : "something5",
prop4 : "something6",
}
]
The array is much bigger than that but you get the idea. I want to display only 5 objects from the array at random each time the code is run which I did like this:
randomArr = arr.sort(() => Math.random() - .5);
spliceArr = randomArr.splice(5);
It works, but it sometimes shows objects from the main array multiple times. How can I write the code so the it will return objects from the array only once?
You could solve this by creating an array of unique random indicies, then return an array of objects that correspond to those random indices.
A set can be used to ensure all generated indices are unique.
function getNRandomObjects(objectArray,numberOfObjects) {
// use a set to ensure at most only one instance of an index is
// generated
const indices = new Set();
while(indices.size < numberOfObjects) {
//generate a random index and add it to the set
indices.add( Math.floor(Math.random() * objectArray.length));
}
// convert the set of indices into an array,
// then map each index to the object that corresponds
// to that index.
return Array.from(indices).map(i=>objectArray[i]);
}