Build a Keyboard-Driven Test Grader in Plain JavaScript

A DEV Community tutorial walks through building a test grader in a single HTML file with no dependencies. Users set the question count once, then record wrong answers with a button or keyboard key while the percentage and letter grade update instantly. The core grading logic lives in a pure function that clamps wrong-answer counts, compares scores using integer cross-multiplication to avoid floating-point errors, and sorts custom grade scales. The page also renders a table of every possible score as a quick chart. The guide additionally covers how to avoid common keyboard shortcut bugs, such as blocking single-letter hotkeys when modifier keys are held or when the user is typing in an input field.