javascript - 如何使console.log（sum（1））// 1和console.log（sum（1,2）（3））// 6工作？(How can I make console.log(sum(1)) // 1 and console.log(sum(1,2)(3)) //6 work?)

Question

sum如何制作console.log（sum（1））// 1和console.log（sum（1,2））// 3和console.log（sum（1,2）（3））// 6工作？

  ask by 道小铿 translate from so

Answer 1

Return a function that, when stringified, returns a number in a closure, which gets added to when the function is called:(返回一个函数，该函数在进行字符串化处理后会在闭包中返回一个数字，该数字会在调用该函数时添加到其中：)

 const sum = (...args) => { let thisSum = 0; const fn = (...args) => { thisSum += args.reduce((a, b) => a + b, 0); return fn; }; fn.toString = () => thisSum; return fn(...args); }; console.log(sum(1)) // 1 console.log(sum(1, 2)) // 3 console.log(sum(1, 2)(3)) //6