EODHD Academy
‹ Build Your First Tool Lesson 12 of 16
Contents Lesson 12 of 16

5 min read · foundations

From a demo list to the tool you actually use

The last step of making it yours is unglamorous and decides whether this thing survives past the course: getting your real instruments in, and finding out which of them this data actually covers.

Find the exact ticker

You know the company; the API needs the identifier, and guessing produces silent holes. The search endpoint answers it:

/search/{query}

Query "vodafone" and you get the listings, each with its exchange suffix, and you pick the one you mean. This matters because the same company on two exchanges is two tickers with two prices, and often two currencies, as unit 2 showed with pence and pounds.

Do this once, while you are building, and paste the results into your list. Do not build a search box into the tool yet. Your list changes a few times a year; a feature for it is scope you have not earned, and your PLAN.md almost certainly has "not building" in the right place already.

Coverage is not universal, and finding out early is cheap

Not every instrument you want is in every plan, and not everything that exists is covered at all. There is a covered-tickers page in this lesson's sources; there is also a faster method, which is to put your whole list in and see what comes back.

This is why unit 2 insisted that a bad ticker fails its own row rather than the list. Import twenty symbols, and the three that come back empty are your answer, immediately and without any research.

The migration moment

Replace the demo list with yours, wholesale:

export const WATCHLIST: string[] = [
  // your instruments, in the order you want to read them
];

Then load the page and look at it properly, because this is the first time the tool is about your money and your attention rather than about the exercise. Three questions:

  1. Is anything missing? Instruments that returned nothing are coverage gaps. Note them; they are one of the things a paid plan changes.
  2. Is the order right? You typed it in the order you thought of them. That is rarely the order you want to read them at 7am.
  3. Would you actually open this? Be honest. If the answer is no, something specific is wrong, and now is the cheapest possible moment to find out what.

Commit this one

Your ticker list is the most personal thing in the repository and it belongs in git: it is not a secret, and you want it back when you clone this on another machine.

git add src/lib/watchlist.ts
git commit -m "My instruments - the ones I check before the open"

Notes and preferences stay in browser storage. Tickers are the tool's configuration; notes are your data. Different lifetimes, different homes.

Try it now

Put every instrument you actually follow into the list, including any that you suspect may not be covered. Load it, and write down two things: which rows came back empty, and what the reading order should be. Fix the order now. Keep the empty list — in the next unit you will find out exactly why they are empty, and what changes it.