Automated Coding Grading Framework – Free JavaScript Test Runner, No Sign-Up

Grading code by eye is slow and inconsistent. This free framework runs student JavaScript against test cases you write and scores it instantly, pass or fail per case. It handles JavaScript only, stated plainly: other languages need a real execution environment. No sign-up. Test-based grading also scales. A teacher with two hundred students cannot read every submission carefully, but a test suite can run every submission identically, and the teacher can spend human time on the interesting failures instead of the routine passes.

What this tool does

Test-based grading is the fairest way to grade code: the same inputs, the same expected outputs, for every student. It removes the temptation to reward code that merely looks tidy.

This tool runs a student function named solve against your cases. Each case passes or fails on its actual output, and the score is the count of passes.

Test grading also teaches debugging. When a student sees exactly which case failed and what the code returned, the fix is often obvious. That feedback loop is worth more than any written comment about style, because it points at behavior, not taste.

How to use it

Paste the student code, defining a function called solve.
Paste test cases, one per line, as arguments | expected output.
Click run tests.
Read the pass/fail table and the score.

Arguments are numbers when they look like numbers, and text otherwise. Keep expected outputs exact: the comparison is a string match on the returned value.

Worked example

Student code “function solve(a, b) { return a + b; }” against cases “2, 3 | 5” and “10, -4 | 6” passes both cases for a score of 2/2.

A student who wrote subtraction instead would fail both cases visibly, and the teacher can point to the exact outputs instead of debating style.

A student function passes five cases but fails the zero case, returning nothing instead of zero. The teacher points to that single row, the student fixes one branch, and the score rises from 5/6 to 6/6 with a lesson about edge cases attached.

Honest limits

This runs JavaScript only, in the browser. Python, Java, and C++ need a server-side execution environment, which a web page tool cannot safely provide. Also, never run code you have not read: this tool executes whatever is pasted.

Tips

Include edge cases in every set: zero, negative numbers, and empty input. Students who only handle the happy path learn quickly when edge cases are graded too.

Common mistakes

The classic mistake is writing tests that only cover the example from the lesson. Students then pass by hardcoding the example answer. Always include at least one case the lesson never showed, so memorized answers fail and real logic passes.

How it fits your week

Write tests when you write the assignment, and publish a few sample tests to students on day one. Students who can check their own work submit stronger code and ask better questions.

Code grading by tests changes the classroom conversation. Instead of debating whether code looks good, teacher and student look together at behavior: what went in, what came out, and what should have come out. That conversation is concrete, fair, and fast, and it teaches the central habit of programming, which is testing your own work. The framework here is deliberately limited to JavaScript, because a browser tool cannot safely run other languages, and stating that limit plainly is part of its honesty. Within that limit, it is a complete grading workflow: write tests with the assignment, share samples early, run submissions, and spend your time on feedback for the cases that failed. Students learn to test, teachers grade consistently, and the scores mean something.

FAQ

Can students use this themselves?
Yes, and they should. Letting students run the same tests before submitting turns grading into feedback and raises scores honestly.

Is test grading fair to creative solutions?
Yes, when tests check behavior rather than implementation. Any code that returns the right outputs passes, however unusual its approach, which rewards creativity instead of punishing it.

Embed this tool on your website — free

Copy the code below to add this working tool to your own page. A small credit link stays with it — that’s all we ask.