See the ES2016 (ES7) standard for full specification of the ECMAScript 2016 language. Practical Learning of New JavaScript Features.
ES2016/ES7
includes the following new features of es 7:
Exponentiation Operator
Performs exponential calculation on operands. Same algorithm as Math.pow(x, y)
Async functions
Deferred Functions. Find the code below
Async generators
Deferred generators.
`// provider
async function* nums() {
yield 1;
yield 2;
yield 3;
}
// consumer
async function printData() {
for(var x on nums()) {
console.log(x);
}
}`Object.getOwnPropertyDescriptors
Returns a property descriptor for an own property.
`// Creating a shallow copy.
var shallowCopy = Object.create(
Object.getPrototypeOf(originalObject),
Object.getOwnPropertyDescriptors(originalObject)
);`Object.values
Get all the values of the object as an array.
`var person = { fname: "Hemanth", lname: "HM", location: "Earth", type: "Human" };
Object.values(person);
//^ ["Hemanth","HM","Earth","Human"]`Object.entries
Returns a Array of arrays of key,value pairs.
`var person = { fname: "Hemanth", lname: "HM", location: "Earth", type: "Human" };
Object.entries(person);
//^ [["fname","Hemanth"],["lname","HM"],["location","Earth"],["type","Human"]]`Array.prototype.includes
Determines whether an array includes a certain element or not.
`[1, 2, 3].includes(3, 0, 7); // true
[1, 2, NaN].includes(NaN); // true
[0,+1,-1].includes(42); // false`Typed Objects
Portable, memory-safe, efficient, and structured access to contiguously allocated data.
`var Point = new StructType({
x: int32,
y: int32
});
var point = new Point({
x: 42,
y: 420
});`Trailing commas in function syntax.
Trailing commas in parameter and argument lists.
`var meow = function (cat1, cat2,) {}
Math.max(4,2,0,);`Class decorators.
Annotate and modify classes and properties at design time.
`class Person {
@cantEnum
get kidCount() { return this.children.length; }
}
function cantEnum(target, name, descriptor) {
descriptor.enumerable = false;
return descriptor;
}`Class properties
Properties of class.
`class Cat {
name = 'Garfield';
static says = 'meow';
}
new Cat().name; // Garfield
Cat.says; // meow`Map.prototype.toJSON
toJSON for Maps.
`var myMap = new Map();
myMap.set(NaN, "not a number");
console.log(myMap.toJSON()); // {"NaN":"not a number"}`Set.prototype.toJSON
toJSON for Sets.
`var mySet = new Set();
mySet.add(NaN);
mySet.add(1);
console.log(mySet.toJSON()) // {"1":1,"NaN":null}`String.prototype.at
String containing the code point at the given position
`'abc\uD834\uDF06def'.at(1) // 'b'
'abc\uD834\uDF06def'.at(3) // '\uD834\uDF06'`Object rest properties
Rest properties for object destructuring assignment.
`let { fname, lname, ...rest } = { fname: "Hemanth", lname: "HM", location: "Earth", type: "Human" };
fname; //"Hemanth"
lname; //"HM"
rest; // {location: "Earth", type: "Human"}`Object spread properties
Spread properties for object destructuring assignment.
`let info = {fname, lname, ...rest};
info; // { fname: "Hemanth", lname: "HM", location: "Earth", type: "Human" }`String.prototype.padLeft
left justify and pad strings.
`"hello".padLeft(4) #=> "hello"
"hello".padLeft(20) #=> "hello "
"hello".padLeft(20, '1234') #=> "hello123412341234123"`String.prototype.padRight
right justify and pad strings.
`"hello".padRight(4) #=> "hello"
"hello".padRight(20) #=> " hello"
"hello".padRight(20, '1234') #=> "123412341234123hello"`String.prototype.trimLeft
left trims the string.
`' \t \n LeftTrim \t\n'.trimLeft(); // 'LeftTrim \t\n';`String.prototype.trimRight
right trims the string.
`' \t \n RightTrim \t\n'.trimRight(); // ' \t \n RightTrim';`Regexp.escape
Escapes any characters that would have special meaning in a regular expression.
`RegExp.escape("(*.*)"); // "\(\*\.\*\)"
RegExp.escape("｡^･ｪ･^｡") // "｡\^･ｪ･\^｡"
RegExp.escape("😊 *_* +_+ ... 👍"); // "😊 \*_\* \+_\+ \.\.\. 👍"`Bind Operator
:: Function binding and method extraction
`let log = (level, msg) => ::console(msg);
import { map, takeWhile, forEach } from "iterlib";
getPlayers()
::map(x => x.character())
::takeWhile(x => x.strength > 100)
::forEach(x => console.log(x));`Author: ven
Reference: Link
