How to Sort a Map by Key or Value in Go

Go maps are unordered, so you must extract keys or values into a slice and sort that slice using the slices package.

import "slices"

m := map[string]int{"b": 2, "a": 1}

// Sort by key
keys := slices.Collect(maps.Keys(m))
slices.Sort(keys)

// Sort by value
entries := make([]struct{ k string; v int }, 0, len(m))
for k, v := range m {
    entries = append(entries, struct{ k string; v int }{k, v})
}
slices.SortFunc(entries, func(a, b struct{ k string; v int }) int {
    return a.v - b.v
})

Maps in Go are like a bag of items where the order doesn't matter. To get them in a specific order, you have to take them out of the bag, put them in a line (a slice), and then arrange that line however you want. This is necessary because the map itself cannot be sorted.