Spread operator

myFunction(...iterableObj

[...iterableObj, 4, 5, 6];

let objClone = { ...obj };

function myFunction(x, y, z) { }
var args = [0, 1, 2];
myFunction.apply(null, args

function myFunction(x, y, z) { }
var args = [0, 1, 2];
myFunction(...args

function myFunction(v, w, x, y, z) { }
var args = [0, 1];
myFunction(-1, ...args, 2, ...[3]

var dateFields = [1970, 0, 1];  // 1 Jan 1970
var d = new Date(...dateFields

function applyAndNew(constructor, args) {
   function partial () {
      return constructor.apply(this, args
   };
   if (typeof constructor.prototype === "object") {
      partial.prototype = Object.create(constructor.prototype
   }
   return partial;
}


function myConstructor () {
   console.log("arguments.length: " + arguments.length
   console.log(arguments
   this.prop1="val1";
   this.prop2="val2";
};

var myArguments = ["hi", "how", "are", "you", "mr", null];
var myConstructorWithArguments = applyAndNew(myConstructor, myArguments

console.log(new myConstructorWithArguments
// (internal log of myConstructor):           arguments.length: 6
// (internal log of myConstructor):           ["hi", "how", "are", "you", "mr", null]
// (log of "new myConstructorWithArguments"): {prop1: "val1", prop2: "val2"}

var parts = ['shoulders', 'knees']; 
var lyrics = ['head', ...parts, 'and', 'toes']; 
// ["head", "shoulders", "knees", "and", "toes"]

var arr = [1, 2, 3];
var arr2 = [...arr]; // like arr.slice()
arr2.push(4 

// arr2 becomes [1, 2, 3, 4]
// arr remains unaffected

var a = [[1], [2], [3]];
var b = [...a];
b.shift().shift( // 1
// Now array a is affected as well: [[], [2], [3]]

var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];
// Append all items from arr2 onto arr1
arr1 = arr1.concat(arr2

var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];
arr1 = [...arr1, ...arr2];

var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];
// Prepend all items from arr2 onto arr1
Array.prototype.unshift.apply(arr1, arr2) // arr1 is now [3, 4, 5, 0, 1, 2]

var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];
arr1 = [...arr2, ...arr1]; // arr1 is now [3, 4, 5, 0, 1, 2]

var obj1 = { foo: 'bar', x: 42 };
var obj2 = { foo: 'baz', y: 13 };

var clonedObj = { ...obj1 };
// Object { foo: "bar", x: 42 }

var mergedObj = { ...obj1, ...obj2 };
// Object { foo: "baz", x: 42, y: 13 }

var obj = {'key1': 'value1'};
var array = [...obj]; // TypeError: obj is not iterable