function once(f, obj) { let count = 0; let result; return function() { count++; if (count == 1) { if (obj == undefined) { obj = {}; } result = f.apply(obj, arguments); } return result; } } let doPayment = once(() => { console.log("生死由命,富贵在天") }) doPayment() //生死由命,富贵在天