ES6 cheat sheet
Template literals embed expressions into strings:
`${ninja}`
.
Function parameters:
■
Rest parameters create an array from arguments that weren’t matched to parameters:
function multiMax(first, ...remaining){ /*...*/}multiMax(2, 3, 4, 5); //first: 2;
remaining: [3, 4, 5]
■
Default parameters specify default parameter values that are used if no value is supplied dur-
ing invocation:
function do(ninja, action = "skulk"){ return ninja + " " + action;}
do("Fuma"); //"Fuma skulk"
Arrow functions let us create functions with less syntactic clutter. They don’t have their own
this
parameter. Instead, they inherit it from the context in which they were created:
const values = [0, 3, 2, 5, 7, 4, 8, 1];
values.sort((v1,v2) => v1 - v2); /*OR*/ values.sort((v1,v2) => { return v1 - v2;});
value.forEach(value => console.log(value));
Promises are placeholders for the result of a computation. A promise is a guarantee that even-
tually we’ll know the result of some computation. The promise can either succeed or fail, and
once it has done so, there will be no more changes:
■
Create a new promise with
new Promise((resolve, reject) => {});
.
■
Call the
resolve
function to explicitly resolve a promise. Call the
reject
function to
explicitly reject a promise. A promise is implicitly rejected if an error occurs.
■
The promise object has a
then
method that returns a promise and takes in two callbacks, a
success callback and a failure callback:
myPromise.then(val => console.log("Success"), err => console.log("Error"));
■
Chain in a
catch
method to catch promise failures:
myPromise.catch(e => alert(e));
.
(continued on inside back cover)
Block-scoped variables:
■
Use the new
let
keyword to create block-level variables:
let ninja = "Yoshi"
.
■
Use the new
const
keyword to create block-level constant variables whose value can’t be
reassigned to a completely new value:
const ninja
=
"Yoshi"
.
Spread operators expand an expression where multiple items are needed:
[...items,
3,
4,
5]
.
Generators generate sequences of values on a per-request basis. Once a value is generated, the
generator suspends its execution without blocking. Use
yield
to generate values:
function *IdGenerator(){
let id = 0;
while(true){ yield ++id; }
}
Lioncatm2016-10-17非常好的一本书, 值得拥有!
今天不熬夜～2020-12-13可以可以，谢谢分享
