CHS-JS1 Cheat Sheet 2026: One-Page Review of Must-Know Facts

The Exam at a Glance

This page condenses what you need to know about the CodeHS JavaScript Level 1 Certification into one scannable review. It covers only this credential: the exam issued and delivered by CodeHS. It is not a course final, not Web Development Level 1, and not a teacher microcredential. If you want the long-form walkthrough, pair this sheet with the CHS-JS1 Study Guide 2026: How to Pass on Your First Attempt.

Two quick arithmetic notes. A 60% threshold on 45 questions works out to 27 correct answers (27 of 45 is exactly 60%), but CodeHS does not publish a scored/unscored item split, so treat that figure as a planning target rather than a guarantee. And 90 minutes across 45 questions gives you an average of two minutes per question, which is generous for multiple-choice code reading but tight if you stall on tracing problems. For more on the threshold itself, see CHS-JS1 Passing Score 2026: Exactly What You Need to Pass.

Data Types and Operators Quick Facts

Domain 1 is where small details decide answers. Questions in this area typically ask you to predict the value or type produced by an expression, so you need fluency with how JavaScript evaluates things rather than just definitions.

Because a calculator is suggested for the exam, expect some questions that involve multi-step arithmetic. Order of operations matters: multiplication, division, and modulus bind tighter than addition and subtraction, and parentheses override everything. When you practice, write out each intermediate result on paper instead of doing it in your head.

Conditionals and Loops Quick Facts

Domains 2 and 3 are the control-flow core of the exam. Most questions here present a short code snippet and ask what it prints, what a variable equals at the end, or how many times a block runs.

Program Structure, Error Handling, and Objects

The last three domains round out the exam. They reward candidates who have actually written and debugged programs, not just read about them. The full topic breakdown lives in CHS-JS1 Exam Domains 2026: Complete Guide to All 6 Content Areas; here is the condensed version.

Domain 4: Program Structure

• Functions: declaring, calling, passing parameters, and returning values. Know the difference between a function that prints a result and one that returns it.
• Scope: variables declared inside a function are not visible outside it.
• Decomposition: why programs are split into small functions and how they call one another.
• Arrays and common operations such as indexing from 0, reading .length, and looping through elements, to the extent your course covered them.
• Reading program flow from the start function or top-level code down through function calls.

Domain 5: Error Handling

• Telling apart syntax errors (code that won't run), runtime errors (code that crashes while running), and logic errors (code that runs but gives the wrong answer).
• Spotting common bugs: off-by-one loop bounds, = versus ==/=== in conditions, missing return statements, misspelled variable names.
• Choosing the fix that actually resolves a described symptom.
• Using try/catch if it appears in your preparation course.

Domain 6: Objects

• Creating objects with key-value properties using curly braces.
• Accessing values with dot notation (student.name) and bracket notation (student["name"]).
• Adding, updating, and reading properties.
• Objects stored inside arrays, and looping through them to read a property from each.
• Methods: properties whose values are functions.

Exam-Day Rules and Logistics

Knowing the rules in advance removes avoidable stress. Here is how testing works.

That last prohibition catches students off guard. Because the exam is code-reading, some candidates are tempted to paste a snippet into a separate editor to see what it does. That counts as a violation. Your tracing has to happen on paper and in your head, which is exactly why practicing that skill beforehand matters. Our How Hard Is the CHS-JS1 Exam? Complete Difficulty Guide 2026 explains why tracing, not syntax recall, is where candidates tend to struggle.

Eligibility is simple: there are no certification prerequisites. The Corgi course is recommended preparation, not a gate. If you want the formal details, read CHS-JS1 Requirements 2026: Eligibility, Prerequisites & How to Qualify.

Vouchers, Retakes, and Results

CodeHS sells certification access to schools and districts through vouchers, and the mechanics affect your planning.

• Pricing: School and district voucher pricing is provided by direct quote from CodeHS. No public numeric fee was verified, so any specific dollar amount you see quoted elsewhere should be treated with suspicion. Our CHS-JS1 Certification Cost 2026: Complete Pricing Breakdown covers how the voucher model works.
• One voucher, one attempt. There is no numerical cap on retakes, but every additional attempt requires another purchased voucher.
• Expiration: Unused school or district vouchers expire at the end of the contract term and do not roll over between school years. If your teacher is holding vouchers, ask when the contract ends before you schedule.
• Scheduling: Because testing runs through a teacher or proctor, your window depends on your school's setup. See CHS-JS1 Exam Dates 2026: Testing Windows, Deadlines & Scheduling for how to approach it.
• Results: Released within 36 hours on school days, with an overall score and a topic-level performance report. That report is your best retake roadmap, since it shows which of the six domains cost you points.
• Certificate: Successful candidates get a downloadable certificate, and earned certificates expire after 10 years.

Sequencing Your Review by Domain

If you only have a few weeks, order your review by dependency, not by the order topics appear on a list. Operators feed conditionals, conditionals feed loops, and nearly everything feeds functions and objects. This is the one place a schedule is worth using, and it is tied directly to the six domains.

Lean on the official Introduction to Computer Science in JavaScript (Corgi) course and the CodeHS Certification Practice course listing for structured practice. Neither defines additional exam domains; they simply give you aligned material to work through. For a fuller breakdown of how to use preparation resources, see CHS-JS1 Training.

Common Traps in JavaScript Tracing Questions

Multiple-choice code questions are built around predictable mistakes. Here are the ones to rehearse against.

1. Off-by-one in loops. A loop from i = 0 to i < 5 runs five times with values 0 through 4. Candidates routinely answer as if it reached 5.
2. String versus number. "10" + 5 is "105", but "10" - 5 is 5. The + operator is the only one that concatenates.
3. Chained versus separate conditionals. Two independent if statements can both execute; an if/else if chain cannot.
4. Print versus return. A function that logs a value doesn't hand it back to the caller. Assigning its result gives you undefined.
5. Zero-based indexing. The last element of a length-5 array is at index 4, not 5.
6. Dot versus bracket notation. Bracket notation takes a string or variable key; dot notation takes a literal property name.
7. Assignment inside a condition. Writing = where === was intended is a classic logic error the exam likes to describe in prose.

Frequently Asked Questions