Overview

Go being a system programming language, features a much richer set of types than JavaScript/TypeScript. This is pretty noticeable when you look at the number types. While in TypeScript there is only one type to represent numbers, number, in Go you’ll find a whole family of them. Each with specific characteristics that make them suitable for different use cases.

There is also 1 specific difference between Go and JavaScript/TypeScript when it comes to variables that is worth mentioning: zero values.

The Zero value

In Go, all types have a zero value.

It is used to give a variable an initial value when you don’t explicitly assign one. The zero value differs from type to type.

E.g. the following TypeScript code would result in NaN (if you ignore the compile errors and run it):

let a: number;
let b = a + 1;
console.log(b); // NaN

However, equivalent Go code would result in 1:

var a int
b := a + 1
fmt.Println(b) // 1

This is because uninitialized variables in Go are implicitly initialized with their zero value. In this case the zero value of int is 0, so a contains the value 0, even though we didn’t specify it explicitly.

When we initialize the b variable, a is 0 (instead of undefined like in JavaScript) so the assignment to b reads 0 + 1.

Zero value overview

Here’s a short overview of the zero values for the most common types in Go:

Type	Zero Value
int	0
float32	0.0
bool	false
string	""
array	[]
struct	{}
map	nil
slice	nil