widespread.js

// section 1
// let sum = function(...args) {
//   return args.reduce((prev,curr)=>prev + curr)
// };

// console.log(sum(2,3,4,5))

// section 2
// let multiply = (mul, ...numbers) => {
//   console.log(mul,numbers)
//   return numbers.map((n) => {
//     return mul*n
//   });
// };

// let result = multiply(2,7,4,5)
// console.log(result)

var numbers = [4, 6, 3, 8];

// we can pass array to Math.max method,
// so we should change the method
// let max = Math.max(numbers) //error

// refer:http://devdocs.io/python~2.7/library/functions#apply
// equivalent Math.max(*args,**kwargs)
// let max = Math.max.apply(null, numbers)
// console.log(max)

// rewrite
var max = Math.max.apply(Math, numbers);
console.log(max);

// concanate
var newNumber = [3, 4, 34, 4].concat(numbers);
console.log(newNumber);