es6笔记干货

/***

es6
*/ { //let [foo, [[bar], baz]] = [1, [[2], 3]];

//console.log(foo) } //{ //let [x,,y]=[1,2,3];

//console.info(x); //} { let name ='shulong';

let age= '23';

// console.log(${name},'名字') } { function add(...add){ let sum = 0;

	for(let val of add){
		sum +=val;
	}
	return sum;
}

// console.log(add(2,5,3)) } { //箭头函数es6箭头 => 代表大括号 let f =() =>5;

//console.log(f());

let sum = (sum1,sum2='2')=>sum1+sum2;

//console.log(sum(1,2));

//箭头函数对应的是数据整合效果，可以添加复制

} { const full = ({first,last})=>first+'last';

//console.log(full());

} { //sperad ... 参数的运算数组用逗号隔开

function push(array,...items){

	array.push(items)
}
let number =[4,38];

//console.log(...number);

} { let birth='2014/10/11';

let Person ={
	name:birth
};

//console.log(Person.name);

} { function sayHello(name="world"){

 //  console.log(`Hello ${name}`);


}
//sayHello();

sayHello('wayou')

} { function add(...x){

	return x.reduce((m,n)=>m+n);
}
//console.log(add(1,2,3)); 

//console.log(add(1,2,3,4,5,6,7,8,9));

} { let person =['wuhan','nanjing','hefen'];

function say (a1,a2,a3){

 // console.log(`hi ${a1},${a2},${a3}`);
};

//say(...person);

} { let s = new Set();//添加不了重复的数字

//console.log(s.add(1).add(2).add(3));//{1,2,3}

let y = new Map();

var e = y.set('hello',32);

//console.info(e); //hello=>32

// console.log(y.set(s));

} { let s = new Set();//添加不了重复的数字 let vm = new WeakMap(); vm.set(s,{extra:42}); let a =vm.size === undefined; //console.log(a);
} { //symblos; //console.log(Number.EPSILON);//对数

console.log(Number.isInteger(Infinity));

let acosh = Math.hypot(3,4);

let hypot = Math.acosh(2);

let imul = Math.imul(Math.pow(2,32)-1 , Math.pow(2,32)-2);

// console.log('abcde'.contains('cd')); //true

let as = 'abc'.repeat(3);

Array.from(document.querySelectorAll('*'));

Array.of(1,2,3);

[0,0,0].fill(7,1);

[1,2,3].findIndex(x =>x ==2); //1

//['a','b','c'].values();

// Object.assign(Point,{origin:new Point(0,0)});

let o =1;

let k=2;

let es5={ o:o, k:k }; let es6 = { o, k }; console.log(es5);

console.log(es6);

} { let es5 ={ hello:function(){

		console.log('hello')
	}
	
};
let es6 = {

	hello(){

		console.log('hello');
	}
}
console.log(es5.hello());

console.log(es6.hello());

} { let a = 'b'; let es5 = { a:'c', b:'c' }; let es6 = { [a]:'c' }

console.log(es5,es6);

} { // object 新增api // console.log('字符串',Object.is('abc','abc'),'abc'==='abc');

// console.log('数组',Object.is([],[]),[]===[]);

// console.log('拷贝',Object.assign({a:'a'},{b:'b'}));

let test = {k:123,o:456};

//拷贝数组键值对

for(let [key,value] of Object.entries(test)){

	//console.log([key,value]);
}

} { //symbol 概念作用

let Symbol1 =Symbol();

let Symbol2 =Symbol();

console.log(Symbol1===Symbol2);

let a3 = Symbol.for('a3');

let a4 = Symbol.for('a3');

console.log(a3===a4);

} { let a1= Symbol.for('abc');

let obj={
	[a1]:'123',
	'abc':345,
	'c':456
};

// console.log(obj); for(let [key,value] of Object.entries(obj)){

	console.log('let ',key,value);

	//拿不到[a1]
	
}
//拿到Symbol
Object.getOwnPropertySymbols(obj).forEach(function(item){

	console.log(obj[item]);
});
//拿到key value
Reflect.ownKeys(obj).forEach(function(e){

	console.log('ownKeys',e,obj[e]);
})

} { let list = new Set();

list.add(5);

list.add(7);

console.log(list.size);

} { let arr =[1,2,3,4,5,'2']; let list2= new Set(arr); console.log(list2); let sta = ['add','delete','clear','has'];

let list = new Set(sta);

// console.log(list.has('add')); //true

// console.log(list.delete('add'));

// console.log(list);

// console.log(list.clear());//清空

// console.log(list);

// for(let key of list.keys()){

// console.log('keys',key);

// } // for(let value of list.values()){

// console.log('values',value);

// } // for(let [key,value] of list.entries()){

// console.log('en',key,value)

// }

} { // console.log("Number",Number.parseFloat === parseFloat);

// const foo = 'bar';

// const baz = {foo};

//baz // {foo:'bar'}

//const baz ={foo:foo};

// function f(x,y){

// // return {x,y};

// }

// function f(x,y){ // // return {x:x,y:y}; // } // 数据结构横向对比增查改删

let map = new Map();

let array = []; map.set('t',1);

array.push({t:1});

console.log('map-array',map,array); //查询 let map_exist = map.has('t'); //true

let array_exist = array.find(item=>item.t);

console.log('map_exist',map_exist,array); // 改 map.set('t',2);

array.forEach(item=>item.t?item.t=2:'');

console.log('map-array-modify',map,array); //删除

map.delete('t');

let index = array.findIndex(item=>item.t);

array.splice(index,1);

console.log('map',map,array);

//set array

let set = new Set();

let arr =[]; //增 set.add({name:"shulonghu"});

arr.push({name:'shulonghu'});

console.log('set-updet',set,arr);

//查 let set_ex = set.has({name:'shulonghu'});

let arr_ex = arr.find(item=>item.name);

console.log('set_ex',set_ex,arr_ex);

//改 set.forEach(item=>item.name?item.name=2:'');

arr.forEach(item=>item.name?item.name=2:'');

console.log('set-array',set_ex,arr_ex); //删 set.forEach(item=>item.name?set.delete(item):'');

let indee = arr.findIndex(item=>item.name);

arr.splice(indee,1);

console.log('/set-arr-empty',set,arr); } { //map set obj let item = {t:1} let map =new Map(); let set =new Set(); let Obj ={};

//增
map.set('t',1);
set.add(item);
set.add(item);
map.set('t',1);
Obj['t']=1;


console.info('map-set-obj',Obj,map,set)
//查
console.info({
	'map':map.has('t'),
	'set':set.has('t'),
	'Obj':'t' in Obj //查询
 });

//改
map.set('t',2);
item.t=2;
Obj['t']= 2;
console.info('mso-modify',Obj,map,set);
// 删

map.delete('t'); set.delete(item); // delete Obj['t']; console.info('mso-del',Obj,map,set); } //f(1,2);

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