var num = 123.45678
console.log(num.toFixed(2)) //123.46

var num2 = 12
console.log(num2.toFixed(2)) //12.00

var num = 123.45678
console.log(num.toFixed(2).replace('.00', '')) //123.46

var num2 = 12
console.log(num2.toFixed(2).replace('.00', '')) //12

var date = new Date()
var min = date.getMinutes()
min = min < 10 ? '0' + min : min
console.log(min) //08

var date = new Date()
var min = String(date.getMinutes()).replace(/^(\d{1})$/, '0$1')
console.log(min) //08

var date = '2017-1-8 12:8'.replace(/\b\d{1}\b/g, '0$&')
console.log(date)

function formatDate (source, format) {
 var date = new Date();
 format = format || 'yyyy-MM-dd hh:mm';
 if (typeof source == 'string') format = source;
 if (typeof source == 'number') date = new Date(source);
 
 let year = date.getFullYear();
 let month = date.getMonth() + 1;
 let day = date.getDate();
 let hour = date.getHours();
 let miniute = date.getMinutes();
 let second = date.getSeconds();
 return format.replace('yyyy', year)
  .replace('MM', month)
  .replace('dd', day)
  .replace('hh', hour)
  .replace('mm', miniute)
  .replace('ss', second)
  .replace(/\b\d{1}\b/g, '0$&');
 return date;
}