任意數求和

 1 function sum(){
 2     let result = null;
 3     for(let i=0; i<arguments.length; i++){
 4         result += arguments[i];
 5     }
 6     return result;
 7 }
 8 console.log(sum(1,2,3));
 9     
10 function fn(){
11     let arr = Array.prototype.slice.call(arguments);
12     return eval(arr.join('+'));
13 }
14 console.log(fn(4,5,6));