Moving from JavaScript to Golang

Variables

Javascript

In Javascript variables can be declared using the let, const(ES6), and var(ES5) keyword.

  // using the const keyword
  const a = 10
  // using the let keyword
  let b = 10
  // using the var keyword
  var c = 10
  console.log(a, b, c) // returns 10, 10, 10

Golang

In Go variables can be declared using the var, const keyword and also using the short syntax.

  // using the var keyword
  var a = 10 // go detects the type here even though we don't specify
  fmt.Println(a) // returns 10
  fmt.Printf("variable a is of type: %T\n", a) // returns int

  // using the const keyword
  const b = 20  // It is important to note that the value of b must be known at compile-time
  fmt.Println(b) // returns 20

  // a variable can be initialized with the var keyword
  var c bool
  fmt.Println(c) // returns the zero value(zero value of a boolean is false)

  // using the short syntax
  d := "this is a variable" // go detects the type of this variable
  fmt.Println(d) // returns this is a variable
  fmt.Printf("d is of type: %T\n", d) // returns the type(string)

Variable Playground

Arrays

An array is a collection of items.

Javascript

In Javascript arrays are dynamic, items can be added and removed from the array, also Javascript being a loosely-typed language, it can hold values of different type in the array.

  let myArray = [1, "this is array", true, 100.30]
  console.log(myArray) // returns [1, "this is array", true, 100.30]

// we can remove the last item in an array using the pop method
  myArray.pop()
  console.log(myArray) // returns [1, "this is array", true]

// we can add to the end of the array using push method
  myArray.push(20)
  console.log(myArray) // returns [1, "this is array", true, 20]

// we can remove the first item of the array using the shift method
  myArray.shift()
  console.log(myArray) // returns ["this is array", true, 20]

// we can add to the start of the array using the unshift method
  myArray.unshift(210)
  console.log(myArray) // returns [210, "this is array", true, 20]

Golang

Arrays are of fixed length in Go, you can’t add nor remove from an array, also an array can only contain the specified type.

    a := [5]string{"a", "b", "c", "d", "e"} // length is 5
    fmt.Println(a) // returns [a b c d e]
    // But what happens if we don't specify exactly 5 items
    b := [5]string{"a", "b", "c"}
    fmt.Printf("%#v", b) // returns [5]string{"a", "b", "c", "", ""}
    // "" represents the zero value(zero value of a string is "")

Array Playground
In Golang we also have slices, they are dynamic and we don’t need to specify the length, values can be added and removed from a slice.

    a := []string{"a", "b", "c"}
    fmt.Printf("%#v", a) //  returns []string{"a", "b", "c"}

    // adding to a slice, we can use the append method to add an item to a slice
    a = append(a, "d")   // append takes in the the array and the value we are adding
    fmt.Printf("%#v", a) // returns []string{"a", "b", "c", "d"}

    // removing from a slice by slicing
    a = append(a[0:3])   // 0 represents the index, while 3 represents the position
    fmt.Printf("%#v", a) // returns []string{"a", "b", "c"}

    // slices can also be created using the make method(in-built)
    // the first value is the type, the second and the third value is the length and maximum capacity of the slice
    b := make([]string, 3, 5)
    fmt.Printf("length of b is:%#v, and cap of b is:%#v\n", len(b), cap(b)) // returns length of b is:3, and cap of b is:5

Slice Playground

Function

Javascript

In Javascript a function expression can we written using the function keyword, arrow function(ES6) can also be used.

// using the function keyword
   function a(value) {
       return value
   }
   const val = a("this is the value")
   console.log(value)
// using arrow function
   const b = ((value) => value) 
   const val2 = b("this is another value")
   console.log(val2)

Golang

Using the func keyword, a function expression can be written in go.

  func a() {
   fmt.Println("this is a function")
}
  a() // returns "this is a function"
// parameters and return type can also be specified
  func b(a,b int) int { // takes in value of type int and returns an int
     result := a * b
   return result
}
  val := b(5,6)
  fmt.Println(val) // returns 30

Function Playground

Objects

Javascript

In JavaScript we can write Objects by specifying the key and the value in curly braces separated by a comma.

  const music = {
   genre: "fuji",
   title: "consolidation",
   artist: "kwam 1",
   release: 2010,
   hit: true
}
console.log(music) // returns {genre: "fuji", title: "consolidation", artist: "kwam 1", release: 2010, hit: true}

Golang

In Golang their is Structs which holds a field and the field type

  type Music struct {
    genre   string
    title   string
    artist  string
    release int
    hit     bool
}
ms := Music{
    genre:   "hiphop",
    title:   "soapy",
    artist:  "naira marley",
    release: 2019,
    hit:     true,
}
fmt.Printf("%#v\n", ms) // returns main.Music{genre:"hiphop", title:"soapy", artist:"naira marley", release:2019, hit:true}

Struct Playground

Helpful Golang resources

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