js函数的几种写法

a:function(e){
}

或者

a:()->{ }

let a="5"
[6,9,4,8,8,6,5,8].add2(n=>n*2);

转老版本

"use strict";

var a = "5"[(6, 9, 4, 8, 8, 6, 5, 8)].add2(function (n) {
  return n * 2;
});

更多
http://babeljs.io/repl/#?babili=false&browsers=&build=&builtIns=false&spec=false&loose=false&code_lz=DYUwLgBAhgvARAVjgKANoDYA0BOTAWTADiMywSIF0A6KAE1oCYAKAOxgD4WAqBgSgG4gA&debug=false&forceAllTransforms=false&shippedProposals=false&circleciRepo=&evaluate=false&fileSize=false&sourceType=module&lineWrap=true&presets=es2015%2Creact%2Cstage-2&prettier=false&targets=&version=6.26.0&envVersion=