ES6常用小技巧总结【去重、交换、合并、反转、

var arr = [1,2,3,4,3,4]; 
var arr2 = [...new Set(arr)];

let [x,y] = [1,2];
[y,x] = [x,y];
console.log(y);

let arr= "hellomybo";
console.log(arr[3]);

let a1 = [1,2,3].map(function (x) {
  return x  x;
});

let a2 = [1,2,3].map(x => x  x);
console.log(a1,a2);

var arr1 = ['a', 'b'];
var arr2 = ['c'];
var arr3 = ['d', 'e'];

// ES5的合并数组
arr1.concat(arr2, arr3);
// [ 'a', 'b', 'c', 'd', 'e' ]

// ES6的合并数组
[...arr1, ...arr2, ...arr3]
// [ 'a', 'b', 'c', 'd', 'e' ]

let str = "12345678900987654321";

str.split('').reverse().join('')

[...str].reverse().join('')

['a',,'b'].filter(x => true)   // ['a','b']

let arr = [1,2,3,4].map(x=>x+1);
console.log(arr);

var arr = [1, [[2, 3], 4], [5, 6]];
var flat = function (a) {
 var length = a.length;
 for (var i = 0; i < length; i++) {
  var item = a[i];
  if (typeof item !== 'number') {
   yield flat(item);
  } else {
   yield item;
  }
 }
};
for (var f of flat(arr)) {
 console.log(f);
}