Node.js

// primitives
const myBool = true;
const myNumber = 10;
const myString = "foo";
const mySymbol = Symbol("bar");
const myNull = null;
const myUndefined = undefined;

// object types
const myObject = {};
const myArray = [];
const myFunction = function () {};
const myError = new Error("error");
const myDate = new Date();
const myRegex = /a/;
const myMap = new Map();
const mySet = new Set();
const myPromise = Promise.resolve();
const myGenerator = function* () {};
const myClass = class {};

Go

package main

func main() {
	// primitives
	var myBool bool = true
	var myInt int = 10
	var myInt8 int8 = 10
	var myInt16 int16 = 10
	var myInt32 int32 = 10
	var myInt64 int64 = 10
	var myUint uint = 10
	var myUint8 uint8 = 10
	var myUint16 uint16 = 10
	var myUint32 uint32 = 10
	var myUint64 uint64 = 10
	var myUintptr uintptr = 10
	var myFloat32 float32 = 10.5
	var myFloat64 float64 = 10.5
	var myComplex64 complex64 = -1 + 10i
	var myComplex128 complex128 = -1 + 10i
	var myString string = "foo"
	var myByte byte = 10  // alias to uint8
	var myRune rune = 'a' // alias to int32

	// composite types
	var myStruct struct{} = struct{}{}
	var myArray []string = []string{}
	var myMap map[string]int = map[string]int{}
	var myFunction func() = func() {}
	var myChannel chan bool = make(chan bool)
	var myInterface interface{} = nil
	var myPointer *int = new(int)
}