Linear search

O(n)

Walk the array once, checking every element in order, when there's no structure to exploit yet.

Signals

unsorted arraycheck every elementno order guaranteefind first/any matchsmall n or one-time scan

Template

function linearSearch(arr, target) {
    for (let i = 0; i < arr.length; i++) {
        if (arr[i] === target) return i;
    }
    return -1;
}

Looks similar, isn't

Binary search: Binary search needs sorted data and n large enough that halving matters. On unsorted input or tiny n, sorting first (or at all) costs more than it saves, so a plain scan wins.

no order guarantee, n up to ~1e4..1e5 with a single scan -> O(n) time, O(1) space. If n is large AND the data is sorted, that's the cue to reach for binary search instead.

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