Skip to content

JavaScript Algorithms: Linear Search

New Course Coming Soon:

Get Really Good at Git

Linear search, also called sequential or simple, is the most basic search algorithm. Given a data structure, for example an array, we search for an item by looking at all the elements, until we find it.

Its implementation is very simple:

const linearSearch = (list, item) => {
  for (const [i, element] of list.entries()) {
    if (element === item) {
      return i

This returns the index of the item we’re looking for. Example:

linearSearch(['a', 'b', 'c', 'd'], 'd') //3 (index start at 0)

If we look for ‘a’, the algorithm will only look at the first element and return, so it’s very fast.

But if we look for the last element, the algorithm needs to loop through all the array. To calculate the Big O value we always look at the worst-case scenario.

So the algorithm complexity is O(n).

Are you intimidated by Git? Can’t figure out merge vs rebase? Are you afraid of screwing up something any time you have to do something in Git? Do you rely on ChatGPT or random people’s answer on StackOverflow to fix your problems? Your coworkers are tired of explaining Git to you all the time? Git is something we all need to use, but few of us really master it. I created this course to improve your Git (and GitHub) knowledge at a radical level. A course that helps you feel less frustrated with Git. Launching May 21, 2024. Join the waiting list!
→ Get my JavaScript Beginner's Handbook
→ Read my JavaScript Tutorials on The Valley of Code
→ Read my TypeScript Tutorial on The Valley of Code

Here is how can I help you: