maps

Node.js

const map = new Map()
map.set('foo', 'bar')
let found = map.has('foo')
console.log(found)
let item = map.get('foo')
console.log(item)
map.delete('foo')
found = map.has('foo')
console.log(found)
item = map.get('foo')
console.log(item)
const map2 = {}
map2['foo'] = 'bar'
item = map2['foo']
delete map2['foo']
const map3 = new Map()
map3.set('foo', 100)
map3.set('bar', 200)
map3.set('baz', 300)
for (let [key, value] of map3) {
  console.log(key, value)
}

Output

true
bar
false
undefined
foo 100
bar 200
baz 300

Go

package main
import "fmt"
func main() {
    map1 := make(map[string]string)
    map1["foo"] = "bar"
    item, found := map1["foo"]
    fmt.Println(found)
    fmt.Println(item)
    delete(map1, "foo")
    item, found = map1["foo"]
    fmt.Println(found)
    fmt.Println(item)
    map2 := make(map[string]int)
    map2["foo"] = 100
    map2["bar"] = 200
    map2["baz"] = 300
    for key, value := range map2 {
        fmt.Println(key, value)
    }
}

Output

true
bar
false
foo 100
bar 200
baz 300