Is the Set.has() method O(1) and Array.indexOf O(n)?
I don't think the array that has 5 elements is good case to check time complexity.
So based on @Shidersz's snippet, I made a new one that has many elements and invoked once.
Is Set.has() really O(1) ?
Yes. Time complexity of Set.has() is O(1) according to result of the test below.
const MAX = 10000000
let a = []
a.length = MAX
for (let i = 0; i < MAX; i++) {
a[i] = i
}
let s = new Set(a)
let o = a.reduce((acc, e) => {
acc[e] = e
return acc
}, {})
console.time("Test_Array.IndexOf(0)\t")
a.indexOf(0);
console.timeEnd("Test_Array.IndexOf(0)\t")
console.time("Test_Array.IndexOf(n/2)\t")
a.indexOf(MAX / 2);
console.timeEnd("Test_Array.IndexOf(n/2)\t")
console.time("Test_Array.IndexOf(n)\t")
a.indexOf(MAX);
console.timeEnd("Test_Array.IndexOf(n)\t")
console.time("Test_Set.Has(0)\t\t")
s.has(0)
console.timeEnd("Test_Set.Has(0)\t\t")
console.time("Test_Set.Has(n/2)\t")
s.has(MAX / 2)
console.timeEnd("Test_Set.Has(n/2)\t")
console.time("Test_Set.Has(n)\t\t")
s.has(MAX)
console.timeEnd("Test_Set.Has(n)\t\t")
console.time("Test_Object[0]\t\t")
o[0]
console.timeEnd("Test_Object[0]\t\t")
console.time("Test_Object[n/2]\t")
o[MAX / 2]
console.timeEnd("Test_Object[n/2]\t")
console.time("Test_Object[n]\t\t")
o[MAX]
console.timeEnd("Test_Object[n]\t\t").as-console {
background-color: black !important;
color: lime;
}
.as-console-wrapper {
max-height: 100% !important;
top: 0;
}