Braily Guzman

Posted on Jun 30

Go for JavaScripters: Why You Should Learn Golang

#programming #go #javascript #devops

Go for JavaScripters: Why You Should Learn Golang

Introduction

Are you a JavaScript developer looking to expand your backend skills, or just curious about a language that powers Docker, Kubernetes, and much of the modern cloud? Meet Go (aka Golang): a language created at Google by Ken Thompson, Rob Pike, and Robert Griesemer to make software development fast, fun, and scalable.

Go is designed for simplicity, speed, and reliability. It compiles to a single binary, has a powerful standard library, and makes concurrency (doing many things at once) a breeze. If you love JavaScript's flexibility but crave more performance and predictability, Go is a perfect next step.

What You'll Learn

How Go compares to JavaScript in syntax and philosophy
Go's type system, variables, and data structures
How to handle strings, bytes, and runes (Unicode!)
Using Go's strings package for text manipulation
Go's powerful concurrency model (goroutines, channels, and more)
Common pitfalls for JS devs switching to Go
How to build and run Go code

Why Learn Go

If you're a JavaScript developer looking to level up with a fast, modern language built for performance and scalability, it's time to meet Go.

Go (or Golang) is a middle-level programming language created at Google in 2007 by engineers who were tired of waiting around for their code to compile and dealing with overly complex systems. The result? A language that combines the performance of C (low-level) with the simplicity and readability of Python (high-level).

Go vs JavaScript: Quick Comparison

Feature	JavaScript	Go
Typing	Dynamic	Static
Compilation	Interpreted/JIT	Compiled (to binary)
Concurrency	Event loop, async/await	Goroutines, channels
Deployment	Needs Node.js runtime	Single binary
Error Handling	try/catch	Explicit error returns
Popular Use Cases	Web, APIs, scripting	APIs, infra, CLI, servers

What is Go Good At?

Go shines when it comes to building fast, scalable backend systems. It's a top choice for writing APIs, web servers, CLI tools, and infrastructure-level software. Tools like Docker, Kubernetes, and Terraform are all written in Go, which says a lot about its speed and reliability.

One of Go's biggest superpowers is concurrency, the ability to run multiple tasks at the same time. In JavaScript, we use async/await and the event loop to handle asynchronous operations. In Go, we use goroutines, lightweight threads that are easy to spawn and manage.

Go also makes deployment a breeze. While Node.js apps often require npm install, package.json, and a dozen dependencies, Go compiles everything into a single binary file you can just drop on a server and run.

When NOT to Use Go

Go is not ideal for:

Front-end/browser-based development

Rapid prototyping with lots of UI

Projects needing generics-heavy data structures (though Go 1.18+ now supports generics, it's not as flexible as TypeScript)

Go might not be ideal for:

Projects that require a lot of dynamic typing or runtime type changes (Go is statically typed and not as flexible as JavaScript or Python for dynamic data structures).
Codebases that rely heavily on advanced generics or metaprogramming (Go's generics are intentionally simple and less expressive than those in TypeScript, Rust, or C++).
Rapid prototyping where developer speed and a huge ecosystem of libraries (like npm for JS or PyPI for Python) are critical. Go's ecosystem is strong but not as broad for every domain.
Projects where you need mature, specialized libraries for things like data science, machine learning, or scientific computing (Go's ecosystem is growing, but not as deep as Python's in these areas).
Teams that require hot-reloading, scripting, or embedding code at runtime (Go is compiled and not designed for scripting or live code changes).

Core Syntax Overview

Hello, World!

JavaScript:

console.log('Hello, World!');

Go:

package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

Variables

JavaScript:

const name = 'Braily';
let age = 18;
let city = 'New York';

Go:

var name string = "Braily"
// Type inference with `var`
var age = 18
// Shorthand declaration
city := "New York"

Go is statically typed, so once a variable has a type, it can't be reassigned to something else, no switching age from a number to a string like in JS.

Data Types

Integers

Unlike JavaScript, which uses a single number type for all integers, Go provides several distinct integer types. Each type has its own range and memory usage, allowing you to choose the most appropriate one for your needs.

Type	Size	Range (approximate)
int8	8-bit	-128 to 127
uint8	8-bit	0 to 255
int16	16-bit	-32,768 to 32,767
uint16	16-bit	0 to 65,535
int32	32-bit	-2.1 billion to 2.1 billion
uint32	32-bit	0 to 4.2 billion
int64	64-bit	-9 quintillion to 9 quintillion
uint64	64-bit	0 to 18 quintillion
int	platform dependent (usually 32 or 64 bits)
uint	platform dependent (unsigned version of int)

For example, if you need to store an RGB (Red, Green, Blue) value ranging from 0 to 255, the best choice is uint8 (an unsigned 8-bit integer), since it efficiently covers exactly that range. If you need to store larger values, simply choose an integer type with a bigger bit size, such as uint16, uint32, or uint64, depending on your requirements.

Key Notes

int will default to 32 or 64 bits depending on your system.
uint types don't allow negative numbers but give you more room for positive values.
Go will catch integer overflows at compile time, not at runtime.

var intNum int16 = 32767 + 1 // Compile-time overflow error

This compiles but causes weird behavior:

var intNum int16 = 32767
intNum += 1
fmt.Println(intNum) // Output: -32768 (wraps around!)

Floating Point

Type	Size	Precision
float32	32-bit	7 digits (single precision)
float64	64-bit	15 digits (double precision — default)

var price float32 = 19.99
var total float64 = 12345678.900000

fmt.Println(price)
fmt.Println(total)

Warning: Precision loss can happen with float32 when dealing with very large or very small decimal values.

Arrays and Slices

Arrays

In Go, arrays have fixed sizes and contain elements of a single type.

var a [3]int = [3]int{1, 2, 3}
fmt.Println(a) // >>> [1 2 3]

You can also let Go infer the length:

b := [...]string{"Go", "is", "cool"}
fmt.Println(b) // >>> [Go is cool]

Key Points:

Arrays are value types. Assigning or passing them copies the whole array.
Their size is part of their type ([3]int != [4]int)

Slices

Slices are more flexible and commonly used than arrays.

nums := []int{10, 20, 30, 40}
fmt.Println(nums) // >>> [10 20 30 40]

You can create a slice from an array:

arr := [5]int{1, 2, 3, 4, 5}
slice := arr[1:4] // elements [2, 3, 4]
fmt.Println(slice)

You can also use make to create a slice with a given length and capacity:

s := make([]int, 3, 5) // len = 3, cap = 5
fmt.Println(s) // >>> [0 0 0]

Slices are references to arrays, so modifying one will affect the original array:

s := []int{1, 2, 3}
s[0] = 99
fmt.Println(s) // [99 2 3]

Append and Slice Tricks

s := []int{1, 2}
s = append(s, 3, 4) // Creates a new array
fmt.Println(s) // >>> [1 2 3 4]

Structs, Types, Methods, and Interfaces

Go uses structs to group related data together, similar to objects in JavaScript. You can also define methods on types (including structs) to add behavior.

Structs Example:

type Person struct {
    Name string
    Age  int
}

func main() {
    p := Person{Name: "Alice", Age: 30}
    fmt.Println(p.Name, p.Age)
}

Methods Example:

type Person struct {
    Name string
}

func (p Person) Greet() string {
    return "Hello, " + p.Name
}

func main() {
    p := Person{Name: "Bob"}
    fmt.Println(p.Greet()) // Output: Hello, Bob
}

What are Interfaces?

Interfaces in Go define a set of method signatures (behavior) that a type must implement. Any type that provides those methods "satisfies" the interface, even if it doesn't explicitly declare that it does. This allows you to write flexible and decoupled code, because functions can accept interfaces rather than concrete types. Interfaces are a key part of Go's approach to polymorphism and code reuse.

What is Duck Typing?

Duck typing is a concept where the type or class of an object is determined by its behavior (methods and properties), not by explicit inheritance or declaration. The phrase comes from "If it walks like a duck and quacks like a duck, it's a duck." In Go, any type that implements the methods required by an interface is considered to satisfy that interface, even if it doesn't explicitly declare it. This is similar to how JavaScript objects can be passed to functions as long as they have the expected methods or properties.

Interfaces Example (Multiple Types):

type Greeter interface {
    Greet() string
}

type Person struct {
    Name string
}

func (p Person) Greet() string {
    return "Hello, " + p.Name
}

type Robot struct {
    ID int
}

func (r Robot) Greet() string {
    return fmt.Sprintf("Beep boop, I am robot #%d", r.ID)
}

func sayHello(g Greeter) {
    fmt.Println(g.Greet())
}

func main() {
    p := Person{Name: "Carol"}
    r := Robot{ID: 42}
    sayHello(p) // Output: Hello, Carol
    sayHello(r) // Output: Beep boop, I am robot #42
}

JavaScript Comparison:
JavaScript doesn't have interfaces, but you can use objects with the same method signatures (duck typing):

function sayHello(greeter) {
  console.log(greeter.greet());
}
const person = {
  name: 'Carol',
  greet() {
    return `Hello, ${this.name}`;
  },
};
const robot = {
  id: 42,
  greet() {
    return `Beep boop, I am robot #${this.id}`;
  },
};
sayHello(person); // Hello, Carol
sayHello(robot); // Beep boop, I am robot #42

Strings, Bytes, and Runes

In JavaScript, strings are sequences of UTF-16 code units. This usually feels like characters but isn't always, especially with emojis or characters from other languages.

In Go, strings are UTF-8 encoded immutable slices of bytes. That means:

A string is a sequence of bytes.
Characters can take up multiple bytes.
Indexing directly gives you a byte, not a character.

Strings (Immutable UTF-8)

greeting := "Hello, 世界"
fmt.Println(greeting)       // >>> Hello, 世界
fmt.Println(len(greeting))  // >>> 13 (bytes, not characters)

Each character in "Hello, 世界" might take 1-3 bytes.
Strings are immutable. You can't change characters via indexing.

Accessing bytes (not characters):

s := "世界"
fmt.Println(s[0])           // >>> 228 (byte, not '世')

[]byte (Raw Bytes)

A byte is an alias for uint8, just a number from 0-255.
[]byte lets you inspect or manipulate the underlying raw data of a string.

word := "résumé"
b := []byte(word)
fmt.Println(b)              // >>> [114 195 169 115 117 109 195 169]
fmt.Println(len(b))         // >>> 8

Compare with JavaScript:

const word = 'résumé';
console.log(word.length); // 6 characters
console.log(Buffer.from(word)); // <Buffer 72 c3 a9 73 75 6d c3 a9>

Runes (Unicode Code Points)

A rune in Go is an int32 representing a full Unicode character, even emojis and symbols from non-Latin scripts.

Useful when dealing with characters, not bytes.
Can handle multi-byte characters like emoji properly.

emoji := "💖"
fmt.Println(len(emoji))       // >>> 4 (bytes)
fmt.Println(utf8.RuneCountInString(emoji)) // >>> 1

Use a []rune to see each character properly:

name := "résumé💖"
runes := []rune(name)

fmt.Println(len(runes))       // >>> 7
fmt.Printf("%q\n", runes)     // >>> ['r' 'é' 's' 'u' 'm' 'é' '💖']

Type Conversions

s := "Go💖"

// string → []byte
b := []byte(s)
fmt.Println(b) // >>> [71 111 240 159 146 150]

// string → []rune
r := []rune(s)
fmt.Println(r) // >>> [71 111 128150]

// []rune → string
fmt.Println(string(r)) // >>> Go💖

Quick Comparison: JavaScript vs Go

Concept	JavaScript	Go
String	`"Go💖"`	`"Go💖"`
Char (Unicode)	`"💖".charCodeAt(0)` → 55357	`rune('💖')` → 128150
Byte length	`Buffer.byteLength("💖")` → 4	`len("💖")` → 4
Char length	`"💖".length` → 2	`utf8.RuneCountInString`
Char array	`Array.from("résumé")`	`[]rune("résumé")`

TL;DR:

What you want	Use this in Go
String of text	`string`
Raw binary data	`[]byte`
Unicode-safe characters	`[]rune`
Count visible characters	`utf8.RuneCountInString(str)`
Loop over characters	`for _, r := range str`

Functions and Control Flow

Functions

JavaScript:

function greet(name) {
  return 'Hello ' + name;
}

Go:

func greet(name string) string {
    return "Hello " + name
}

In Go, you must declare the type of each parameter and the return value. The function block is enclosed by {} just like JS.

Returning Multiple Values

Go functions can return more than one value, which is commonly used for returning a result and an error.

func divide(a, b float64) (float64, error) {
    if b == 0 {
        return 0, fmt.Errorf("cannot divide by zero")
    }
    return a / b, nil
}

result, err := divide(10, 2)
if err != nil {
    fmt.Println("Error:", err)
} else {
    fmt.Println("Result:", result)
}

JavaScript Comparison:

In JavaScript, you might return an object or array to simulate multiple return values:

function divide(a, b) {
  if (b === 0) return [null, 'cannot divide by zero'];
  return [a / b, null];
}

const [result, error] = divide(10, 2);
if (error) {
  console.log('Error:', error);
} else {
  console.log('Result:', result);
}

Conditionals

Go uses familiar if/else logic but requires the conditions to evaluate to a bool, no more truthy/falsy magic like in JS.

if age >= 18 {
    fmt.Println("You're an adult!")
} else {
    fmt.Println("You're still a minor!")
}

Pointers

Go uses pointers to reference memory locations, similar to C, but without pointer arithmetic. Pointers are useful for modifying values in place and for efficient memory usage.

Example:

func increment(n *int) {
    *n = *n + 1
}

num := 5
increment(&num)
fmt.Println(num) // Output: 6

*int means "pointer to an int".
&num gets the address of num.
*n dereferences the pointer to access the value.

JavaScript Comparison:
JavaScript does not have pointers, but objects and arrays are passed by reference:

function increment(obj) {
  obj.value++;
}
let num = { value: 5 };
increment(num);
console.log(num.value); // 6

Loops

Go has only one loop keyword: for.

for i := 0; i < 5; i++ {
    fmt.Println(i)
}

You can also use it like a while loop:

x := 0

for x < 3 {
    fmt.Println(x)
    x++
}

Using range

The range keyword is used to iterate over elements in a variety of data structures, including arrays, slices, maps, and strings. When iterating over a string, range yields the index and the Unicode code point (rune) at each position.

Example: Iterating over runes in a string

str := "Go💖"
for i, r := range str {
    fmt.Printf("Index: %d, Rune: %c, Unicode: %U\n", i, r, r)
}

This will print each Unicode character (rune) in the string, including multi-byte characters like emojis.

Working with the strings Package

Go's standard library includes the powerful strings package for manipulating text. Here are some common tasks:

import (
    "fmt"
    "strings"
)

func main() {
    s := "  Hello, Go!  "
    fmt.Println(strings.ToUpper(s))           // "  HELLO, GO!  "
    fmt.Println(strings.TrimSpace(s))         // "Hello, Go!"
    fmt.Println(strings.Contains(s, "Go"))    // true
    fmt.Println(strings.HasPrefix(s, "  H"))  // true
    fmt.Println(strings.ReplaceAll(s, "Go", "Gophers")) // "  Hello, Gophers!  "
    fmt.Println(strings.Split(s, ","))        // ["  Hello" " Go!  "]
}

JavaScript Comparison:

const s = '  Hello, Go!  ';
console.log(s.toUpperCase()); // "  HELLO, GO!  "
console.log(s.trim()); // "Hello, Go!"
console.log(s.includes('Go')); // true
console.log(s.startsWith('  H')); // true
console.log(s.replaceAll('Go', 'Gophers')); // "  Hello, Gophers!  "
console.log(s.split(',')); // ["  Hello", " Go!  "]

Concurrency in Go: Goroutines, Channels, WaitGroups, and Mutexes

Go's concurrency model is one of its superpowers. Unlike JavaScript's single-threaded event loop, Go lets you run multiple tasks at the same time using goroutines and channels.

Concurrency vs Parallelism

Concurrency is about dealing with lots of things at once (structuring your program to handle multiple tasks that may not actually run at the same time).
Parallelism is about doing lots of things at the same time (actually running on multiple CPU cores).

Go makes it easy to write concurrent code, and if your machine has multiple cores, Go can run goroutines in parallel too.

Goroutines

A goroutine is a lightweight thread managed by the Go runtime. Just add go before a function call to run it concurrently:

package main

import (
    "fmt"
    "time"
)

func sayHello() {
    fmt.Println("Hello from a goroutine!")
}

func main() {
    go sayHello() // runs concurrently
    fmt.Println("Main function")
    time.Sleep(time.Second) // Give goroutine time to run
}

Channels

Channels let goroutines communicate safely:

package main

import (
    "fmt"
)

func main() {
    ch := make(chan string)
    go func() {
        ch <- "Hello from goroutine"
    }()
    msg := <-ch
    fmt.Println(msg)
}

ch <- value sends a value into the channel.
<-ch receives a value from the channel.

WaitGroup

A sync.WaitGroup lets you wait for a group of goroutines to finish:

package main

import (
    "fmt"
    "sync"
)

func worker(id int, wg *sync.WaitGroup) {
    defer wg.Done()
    fmt.Printf("Worker %d done\n", id)
}

func main() {
    var wg sync.WaitGroup
    for i := 1; i <= 3; i++ {
        wg.Add(1)
        go worker(i, &wg)
    }
    wg.Wait() // Wait for all workers to finish
    fmt.Println("All workers done")
}

Mutex

A sync.Mutex is used to safely share data between goroutines:

package main
import (
    "fmt"
    "sync"
)

func main() {
    var mu sync.Mutex
    count := 0
    var wg sync.WaitGroup
    for i := 0; i < 1000; i++ {
        wg.Add(1)
        go func() {
            mu.Lock()
            count++
            mu.Unlock()
            wg.Done()
        }()
    }
    wg.Wait()
    fmt.Println("Final count:", count)
}

Why use a mutex? Without it, multiple goroutines could try to update count at the same time, causing race conditions.

defer

The defer keyword in Go schedules a function call to run after the function completes, just before it returns. This is especially useful for cleanup tasks like closing files, unlocking mutexes, or printing final messages.

Example: File closing

package main
import (
    "fmt"
    "os"
)

func main() {
    f, err := os.Open("file.txt")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    defer f.Close() // Will run at the end of main, even if there's a return or panic
    fmt.Println("File opened!")
    // ... do work with file ...
}

Example: Multiple defers

If you use multiple defer statements, they run in LIFO (last-in, first-out) order:

func main() {
    defer fmt.Println("first")
    defer fmt.Println("second")
    fmt.Println("main body")
}
// Output:
// main body
// second
// first

Common uses:

Closing files or network connections
Unlocking mutexes
Logging or printing final messages

JavaScript Comparison:
JavaScript doesn't have a direct equivalent, but you might use finally in a try/catch/finally block for similar cleanup:

try {
  // ... work ...
} finally {
  // cleanup code
}

Common Gotchas for JS Devs

No implicit type coercion: Go won't convert types for you. "5" + 1 is an error, not "51".
Zero values: Uninitialized variables have a default value (e.g., 0 for int, "" for string, nil for pointers/slices/maps).
No exceptions: Go uses explicit error returns, not try/catch.
No variable hoisting: All variables must be declared before use.
No unused imports or variables: The compiler will error if you import a package or declare a variable and don't use it.
No classes: Use structs and interfaces instead.
No method overloading or default parameters.

Mini Project: Word Counter CLI

Let's build a simple CLI tool that reads a line of text from the user, counts the number of words and unique words, and prints word frequencies. This demonstrates string manipulation, maps, and user input.

package main

import (
    "bufio"
    "fmt"
    "os"
    "strings"
)

func main() {
    reader := bufio.NewReader(os.Stdin)
    fmt.Print("Enter a sentence: ")
    line, _ := reader.ReadString('\n')
    line = strings.TrimSpace(line)
    words := strings.Fields(line)

    wordCount := make(map[string]int)
    for _, word := range words {
        wordCount[word]++
    }

    fmt.Printf("Total words: %d\n", len(words))
    fmt.Printf("Unique words: %d\n", len(wordCount))
    fmt.Println("Word frequencies:")
    for word, count := range wordCount {
        fmt.Printf("%s: %d\n", word, count)
    }
}

Why not use fmt.Scanf for user input?

fmt.Scanf is best for simple, space-separated input (e.g., numbers or single words), but for names or sentences, bufio.Reader is preferred because it reads the whole line, including spaces. fmt.Scanf will only read up to the first space.

Go Modules & Project Structure

Go uses modules to manage dependencies. To start a new project:

go mod init github.com/yourusername/yourproject

Typical Go project structure:

myproject/
  go.mod
  main.go
  pkg/      # reusable packages
  internal/ # private packages

Error Handling in Go

Go does not use exceptions. Instead, functions that can fail return an error as a second return value:

val, err := strconv.Atoi("123")
if err != nil {
    fmt.Println("Conversion failed:", err)
} else {
    fmt.Println("Value:", val)
}

Simple HTTP Server Example

Go makes it easy to spin up a web server:

package main
import (
    "fmt"
    "net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello from Go!")
}

func main() {
    http.HandleFunc("/", handler)
    fmt.Println("Server running at http://localhost:8080/")
    http.ListenAndServe(":8080", nil)
}

Next Steps & Resources

JavaScript to Go: Quick Reference Cheat Sheet

JavaScript Concept	Go Equivalent
`let` / `const`	`var` / `:=`
Array	Slice (`[]type`)
Object	Struct
Function	`func`
Class	Struct + Methods
Interface (TypeScript)	Interface
`null` / `undefined`	`nil`
`Promise` / `async/await`	Goroutine + Channel
Exception (`try/catch`)	Multiple return values + `error`
`finally`	`defer`
`for...of`	`for _, v := range ...`
`for...in`	`for k := range ...`
`Object.keys(obj)`	`for k := range map`
`console.log`	`fmt.Println`

Conclusion

Go is a modern, efficient, and fun language that empowers JavaScript developers to build fast, scalable, and reliable backend systems. With its simple syntax, powerful concurrency model, and robust standard library, Go is a fantastic next step for anyone looking to level up their programming skills.

If you’re comfortable in JavaScript, you’re more ready for Go than you think. The syntax is different, but the logic and problem-solving skills you’ve built in JS will serve you well.

Ready to try Go? Dive into the resources above, experiment with the examples, and start building something awesome. Happy coding! 🚀

Have questions or feedback? Feel free to reach out or leave a comment!

Top comments (1)

arhuman • Jul 1 • Edited

Great article!

If you allow me, I'd add few things I would love to know when I learned Go:

Go is data centric, forget about prototype/OOP thinks in terms of struct/method
Embrace interfaces, they are more than just your way to polymorphism, they are your api contract, testability guarantee so at the end your refactoring best friend
Don't be obsessed by the perfect code layout, many newcomers soon discover that none emerged as THE layout (even the misnamed standard layout): takes the pieces that are commons and suit you. (Go allow you quite easily to move files around if you know how to avoid circular references)

Table of Contents

Introduction

What You'll Learn

Why Learn Go

Go vs JavaScript: Quick Comparison

What is Go Good At?

When NOT to Use Go

Core Syntax Overview

Hello, World!

Variables

Data Types

Integers

Key Notes

Floating Point

Arrays and Slices

Arrays

Slices

Structs, Types, Methods, and Interfaces

Strings, Bytes, and Runes

Strings (Immutable UTF-8)

[]byte (Raw Bytes)

Runes (Unicode Code Points)

Type Conversions

Quick Comparison: JavaScript vs Go

Functions and Control Flow

Functions

Returning Multiple Values

Conditionals

Pointers

Loops

Using range

Working with the strings Package

Concurrency in Go: Goroutines, Channels, WaitGroups, and Mutexes

Concurrency vs Parallelism

Goroutines

Channels

WaitGroup

Mutex

defer

Common Gotchas for JS Devs

Mini Project: Word Counter CLI

Go Modules & Project Structure

Error Handling in Go

Simple HTTP Server Example

Next Steps & Resources

JavaScript to Go: Quick Reference Cheat Sheet

Conclusion