let a1 = {key1:"key1",key2:"key2",key2:"key2",key3:"key3",key3:"key3"};
let b1 = Object.assign({},a1)
console.log(JSON.stringify(b1));
let a2 = [1,2,2,3,3,4,4,5];
let b2 = Array.from(new Set(a2));
console.log(b2)
let c2 = [...new Set(a2)];
console.log(c2)
let a3 = [
{key:"1",name:"甲"},
{key:"2",name:"乙"},
{key:"3",name:"丙"},
{key:"4",name:"丁"},
];
let b3 = Array.from(a3,({name})=>name);
let c3 = Array.from(a3,(item)=>item.name);
console.log(b3)
console.log(c3)
a3.length = 0;
a2 = {...a2};
console.log(JSON.stringify(a2));
let a4=[1,2];
let b4=[3,4];
console.log([...a4,...b4])
let a5 = [0,2,4,6,8,8];
let b5 = [1,2,3,4,5,6];
let c5 = [...new Set(a5)].filter((item)=>b5.includes(item));
console.log(c5);
let a6 = [0,'blue','',NaN,9,true,undefined,false];
let b6 = a6.filter((item)=>item)
console.log(b6)
let c6 = a5[(Math.floor(Math.random()*(a5.length)))];
console.log(c6)
let sum5 = a5.reduce((x,y)=>x+y);
console.log(sum5)
console