JavaScript Developer Cert Lab

25lessons weighted like the exam, so your hours go where the points are

647practice questions that explain every answer

4timed practice exams that show you're ready before you book

$9.99for 12 months, with a 30-day refund

What the JavaScript Developer cert can do for you

Salesforce Certified JavaScript Developer says you know the language itself, in the browser and on the server, not just one framework. Here's what people usually want from it, and how this course helps you get there.

Proof your JavaScript is solid

It's a credential anyone can verify with Salesforce, covering the language, the browser, Node.js and testing. That's something concrete for your next review, résumé or rate conversation.

A bridge into Salesforce development

Lightning Web Components are standard JavaScript. The exam has no prerequisite, so web developers can use it to show they're ready for Salesforce front-end work.

The person who fixes the weird bug

When a value is undefined, this points at the wrong object or logs come out in the wrong order, you'll know why and what to change.

Walking into the exam calm

By exam day you'll have taken 4 full practice exams on a 105-minute timer, so you'll know where you stand against the 65% pass mark before you pay the $200 fee.

Every feature, and what it does for you

Lessons weighted like the exam

25 lessons follow the official exam guide's 7 sections and weights. Objects, Functions, and Classes is the biggest at 25%, so it gets the most lessons.

10 questions after every lesson

You find out right away whether a lesson stuck, while it's still fresh, instead of finding the gap on exam day.

Every answer explained

Each question explains why the right answer is right and why the other options are wrong, so a snippet you've never seen before still makes sense.

Code you read like you do at work

Editor-style code blocks and short Try it tasks you run in your browser console or Node.js. No paid tools needed.

A section check, flashcards and a practice quiz per section

Short, self-contained study sessions. Ten minutes of flashcards on a lunch break still moves you forward when your week is full.

4 full practice exams

60 questions, a 105-minute timer and the real 65% pass mark. Your results show which sections need work, so you book with evidence instead of hope.

Get the JavaScript Cert Lab, $9.99 Try a free lesson →

What you'll be able to do

The exam tests whether you can predict what JavaScript code does. Here's what you'll know when you finish, and why it matters at work.

Predict coercion, equality, truthiness and array results without running the code.
Know what this, closures, prototypes and classes do in any call site.
Handle events, the DOM, storage and fetch the way the browser actually behaves.
Order promise callbacks, async/await and timers correctly in the event loop.
Find bugs fast with DevTools breakpoints, the console and proper error handling.
Run Node.js and npm with confidence and write Jest tests that catch real bugs.

Try one before you buy

This is the kind of snippet the exam uses, and the kind you'll practice. In what order do the letters print?

order.js

1console.log('A');
2setTimeout(() => console.log('B'), 0);
3Promise.resolve().then(() => console.log('C'));
4(async () => {
5  console.log('D');
6  await null;
7  console.log('E');
8})();
9console.log('F');

Show the answer

A, D, F, C, E, B. Synchronous code runs first, including the async function up to its await. Then the microtasks run in the order they were queued: the promise callback (C), then the code after await (E). The timer (B) is a task, so it runs last even with a 0 ms delay. In the course, every question explains each option like this and links to the docs behind it.

Your 6-week plan

A suggested schedule of about 5 hours a week, then a week of practice exams. Go faster or slower, you have 12 months. Each section ends with a section check, flashcards and a practice quiz, so you know it stuck before you move on.

Week 1

Variables, Types, and Collections

var, let and const, strings, numbers and dates, coercion and equality, truthy and nullish values, arrays and JSON.

Week 2

Objects, Functions, and Classes

The biggest section. Functions and parameters, this and bind, prototypes, classes, modules, scope and closures.

Week 3

Browser and Events

Events and propagation, the DOM, DevTools panels, and browser APIs like storage, fetch, timers and history.

Week 4

Asynchronous Programming, Debugging and Error Handling

Promises and combinators, async/await and the event loop, then try/catch, the console and breakpoints.

Week 5

Server Side JavaScript and Testing

Node.js, its core modules and CLI, npm and package.json, then effective Jest unit tests.

Week 6

Practice exams and review

Take the timed practice exams. Your results point to your weak sections, so your last hours go exactly where you need them.

Start week 1 today

You're enrolled right after checkout. Or try a free lesson and see if the format fits you.

$9.9912 months

Start week 1, $9.99 Try a free lesson

Why a plan built on practice works

Pulling an answer out of memory strengthens it more than rereading does. Researchers call it retrieval practice. In a 2006 study by Roediger and Karpicke, students who practiced recall remembered about 61% a week later, against about 40% for students who reread. Read more in The Science of Studying for Salesforce Certifications.

That's why every part of this course asks you to answer, not just read: lessons, section checks, flashcards, quizzes and practice exams.

See exactly what you'll study

7 sections · 25 lessons · 647 practice questions · 4 practice exams. Try a free lesson before you decide.

Start here · study guide

JavaScript Developer study guide🔒 Locked

Variables, Types, and Collections · 23% · 6 lessons

VT1: Declaring variables with var, let and const🔒 Locked
VT2: Strings, numbers and dates🔒 Locked
VT3: Type coercion and equality🔒 Locked
VT4: Truthy, falsy, nullish and optional chaining🔒 Locked
VT5: Working with arrays🔒 Locked
VT6: Working with JSON🔒 Locked
Section check, flashcards and a 14-question practice quiz🔒 Locked

Objects, Functions, and Classes · 25% · 6 lessons

OF1: Functions: declarations, expressions, arrows and parameters🔒 Locked
OF2: this, call, apply and bind🔒 Locked
OF3: Objects, properties and the prototype chain🔒 Locked
OF4: Classes, inheritance, getters and private fields🔒 Locked
OF5: Modules: import and export🔒 Locked
OF6: Scope and closures🔒 Locked
Section check, flashcards and a 15-question practice quiz🔒 Locked

Browser and Events · 17% · 4 lessons

BE1: Events: listeners, propagation and custom events🔒 Locked
BE2: Working with the DOM🔒 Locked
BE3: Browser DevTools: Elements, Network, Performance and Memory🔒 Locked
BE4: Browser APIs: storage, fetch, timers, location and history🔒 Locked
Section check, flashcards and a 10-question practice quiz🔒 Locked

Debugging and Error Handling · 7% · 2 lessons

DE1: Handling errors with try, catch, finally and throw🔒 Locked
DE2: Debugging with the console and breakpoints🔒 Locked
Section check, flashcards and a 8-question practice quiz🔒 Locked

Asynchronous Programming · 13% · 3 lessons

AP1: Promises, chaining and the combinators🔒 Locked
AP2: async and await🔒 Locked
AP3: The event loop, tasks and microtasksTry a free lesson
Section check, flashcards and a 10-question practice quiz🔒 Locked

Server Side JavaScript · 8% · 2 lessons

SS1: Node.js: the runtime, the CLI and core modules🔒 Locked
SS2: npm, package.json and choosing a framework🔒 Locked
Section check, flashcards and a 8-question practice quiz🔒 Locked

Testing · 7% · 2 lessons

TS1: Writing effective unit tests with Jest🔒 Locked
TS2: Mocks, hook scope and async error tests🔒 Locked
Section check, flashcards and a 8-question practice quiz🔒 Locked

Practice exams · 4 full exams · 60 questions each

Practice Exam 1: 60 questions, 105-minute timer🔒 Locked
Practice Exam 2: 60 questions, 105-minute timer🔒 Locked
Practice Exam 3: 60 questions, 105-minute timer🔒 Locked
Practice Exam 4: 60 questions, 105-minute timer🔒 Locked

Try a free lesson Unlock every section, $9.99

How it's built

The lessons start where developers lose points on this exam: coercion, this, closures and the order of async callbacks. It's not a syntax drill.

Every fact and code sample in the course is checked against MDN Web Docs, Node.js, npm, Jest, Chrome DevTools docs or Trailhead, and each lesson lists its sources. If a fact can't be sourced, it isn't in the course.

Is it right for you?

You build Lightning Web Components

You write JavaScript every day. This fills in the language details the exam asks about and LWC work rarely shows you.

You're a web developer new to Salesforce

There's no prerequisite. Your JavaScript experience counts, and the course shows you exactly how the exam asks about it.

You've done Trailhead and want exam-style practice

Badges teach the topics. This adds hundreds of exam-style questions with the reasoning behind each answer, and timed practice exams that tell you when you're ready.

You're retaking after a miss

Timed, exam-weighted practice exams show which sections cost you points, so you can fix those before you pay the $100 retake fee.

Who it's not for

Anyone looking for real exam questions. There are none here. It also isn't a first course in programming. It assumes you've written some JavaScript before.

Everything you get

25 lessons across all 7 exam sections, plus a study guide Every section covered, in proportion to its weight on the exam	✓
647 practice questions with explanations: 250 in lessons, 84 in section checks, 73 in 7 practice quizzes, 240 in practice exams Enough repetition that the right answer comes quickly under time pressure	✓
4 full practice exams of 60 questions each, timed at 105 minutes Know your score before you book the exam	✓
A section check and flashcards for every section Quick reviews that fit into a short break	✓
Code samples and Try it tasks for your browser console or Node.js See the behavior yourself with free tools	✓
Every answer explained, with links to the official docs Learn the reason, then check the source yourself	✓
12 months of access Study at your own pace and come back to review later	✓
30-day refund If it isn't for you, email us and get your money back	✓
Your price The exam itself is $200	$9.99 12 months

For comparison, the exam costs $200 and a retake costs $100, according to the official Salesforce exam guide.

Get the JavaScript Cert Lab, $9.99

✓ 30-day refund

Questions

How much does the JavaScript Developer Cert Lab cost?

$9.99 for 12 months of access to every lesson, quiz and practice exam.

How long does it take to study for the JavaScript Developer exam with Cert Lab?

About 28 hours, or roughly 6 weeks at 5 hours a week, based on the lessons, section quizzes and 4 practice exams in the course.

What's in the practice exams?

4 full practice exams of 60 questions each, 105 minutes each, weighted by section like the official exam guide. After you submit, you see the correct answers and an explanation for every question.

Do I need Salesforce experience for the JavaScript Developer exam?

No. The exam has no prerequisite and tests JavaScript itself: the language, the browser, Node.js and testing.

Is this the same exam as JavaScript Developer I?

Yes. Trailhead's prep modules still use the name Salesforce JavaScript Developer I for the exam now listed as Salesforce Certified JavaScript Developer.

Why do practice tests help?

Retrieving an answer from memory makes it stick better than rereading. This is called retrieval practice, or the testing effect.

Do I need a Salesforce certification first?

No. The JavaScript Developer exam has no prerequisite.

What is the passing score for the JavaScript Developer exam?

65% on 60 scored questions in 105 minutes, according to the official Salesforce exam guide.

Is this the same as JavaScript Developer I?

Yes. Trailhead's prep modules still use the name Salesforce JavaScript Developer I for this exam.

Do I need any paid software?

No. Every Try it task runs in your browser console or in Node.js, which is free.

How soon can I start?

Right after checkout. You're enrolled as soon as your payment goes through.

How long do I have access?

12 months from the day you buy.

What if it's not for me?

Email refunds@nickfrates.com within 30 days for a full refund. See the refund policy.

Are these real exam questions?

No. Every snippet and question is written from the public exam objectives and the official docs. Using real exam questions breaks Salesforce's certification agreement.

Earn the cert, and write JavaScript you can explain.

Pass the exam, bring sharper debugging to your next project and give yourself a credential you can point to.

$9.9912 months of access ✓ 30-day refund

Start the JavaScript Cert Lab, $9.99

Not ready to buy? Try a free lesson and judge it for yourself.

Pass JavaScript Developer and prove your JavaScript holds up.

What the JavaScript Developer cert can do for you

Proof your JavaScript is solid

A bridge into Salesforce development

The person who fixes the weird bug

Walking into the exam calm

Every feature, and what it does for you

Lessons weighted like the exam

10 questions after every lesson

Every answer explained

Code you read like you do at work

A section check, flashcards and a practice quiz per section

4 full practice exams

What you'll be able to do

Try one before you buy

Your 6-week plan

Variables, Types, and Collections

Objects, Functions, and Classes

Browser and Events

Asynchronous Programming, Debugging and Error Handling

Server Side JavaScript and Testing

Practice exams and review

Start week 1 today

Why a plan built on practice works

See exactly what you'll study

How it's built

Is it right for you?

You build Lightning Web Components

You're a web developer new to Salesforce

You've done Trailhead and want exam-style practice

You're retaking after a miss

Who it's not for

Everything you get

Questions

Earn the cert, and write JavaScript you can explain.

About Course

Who it's for

What it costs

How long it takes

What you get out of it

Why practice tests work

Pass mark and exam format

Former names

FAQ

How much does the JavaScript Developer Cert Lab cost?

How long does it take to study for the JavaScript Developer exam with Cert Lab?

What's in the practice exams?

Do I need Salesforce experience for the JavaScript Developer exam?

Is this the same exam as JavaScript Developer I?

Why do practice tests help?

Course Content

Start here: Study guide

JavaScript Developer study guide

Variables, Types, and Collections (23%)

VT1: Declaring variables with var, let and const

VT2: Strings, numbers and dates

VT3: Type coercion and equality

VT4: Truthy, falsy, nullish and optional chaining

VT5: Working with arrays

VT6: Working with JSON

Variables, Types, and Collections: Section check

Variables, Types, and Collections: Flashcards

Variables, Types, and Collections: Practice Quiz

Objects, Functions, and Classes (25%)

OF1: Functions: declarations, expressions, arrows and parameters

OF2: this, call, apply and bind

OF3: Objects, properties and the prototype chain

OF4: Classes, inheritance, getters and private fields

OF5: Modules: import and export

OF6: Scope and closures

Objects, Functions, and Classes: Section check

Objects, Functions, and Classes: Flashcards

Objects, Functions, and Classes: Practice Quiz

Browser and Events (17%)

BE1: Events: listeners, propagation and custom events

BE2: Working with the DOM

BE3: Browser DevTools: Elements, Network, Performance and Memory

BE4: Browser APIs: storage, fetch, timers, location and history

Browser and Events: Section check

Browser and Events: Flashcards

Practice Exams
Your first attempt is your real score. Each practice exam has a fixed set of 60 questions, so later attempts measure memory, not readiness. Take each exam once under the 105-minute timer, aim for 65% or higher, then review the sections you missed.