如何在javascript中从yyyymmddhhmmss格式中获取时间

Question

YYYYMMDDHHMMSS FORMAT

var d = new Date("20180101120000");

var k = d.toString().slice(8,10);
var l = d.toString().slice(10,12);
var m = d.toString().slice(12,14);

document.getElementById("demo").innerHTML = k + ":" + l + ":" + m +" " ;

<div id='demo'></div>