从构造函数启动单个实例,并将其用作另一个类中的静态方法

class Util {
  constructor () {
    this.numberFormatter = new Intl.NumberFormat('en-US');
  }
}

const util = new Util;

const formatter = util.numberFormatter;
const formatter2 = util.numberFormatter;

console.log(formatter1 === formatter2);

class Util {
  constructor(locale) {
    this.numberFormater = new Intl.NumberFormat(locale);
  }
  static numberFormater() {
    return this.numberFormatter;
  }
}

var a = new Util('en-US');
console.log(a.numberFormater.format);