Let's Learn ES6 - Spread Operator and Rest Parameters

01-Spread Operator-and-Rest-Parameters-reduce.js

//1
let sum = function(){  
  var method = (prev,curr)=>{
    return prev+curr;
  };  
  return Array.prototype.reduce.call(arguments,method);
};
console.log(sum(1,2,3,4));
/*
output:
10
*/

//////////////////////
//2-A
let sum = function(...args){  
  var method = (prev,curr)=>{
    return prev+curr;
  };  
  return args.reduce(method);
};
console.log(sum(1,2,3,4));
//////////////////////
//2-B
let sum = function(...args){  
  var method = (prev,curr) => prev+curr;  
  return args.reduce(method);
};
console.log(sum(1,2,3,4));
//////////////////////
//2-C
let sum = function(...args){    
  return args.reduce((prev,curr) => prev+curr);
};
console.log(sum(1,2,3,4));
/*
output:
10
*/

02-Spread Operator-and-Rest-Parameters-sum.js

//1
let sum = function(... args){  
  console.log(args);
  
};
sum(1,2,3,4);
/* output:
[1, 2, 3, 4]
*/

03-Spread Operator-and-Rest-Parameters-multiply.js

let multiply = (mul,...numbers)=>{
  return numbers.map(n=>{
    return mul*n;
  });
};
let result = multiply(10,1,2,3);
console.log(result);
/**output:
[10, 20, 30]
**/