reduce es6 array code example

Example 1: reduce object to array javascript

var arr = [{x:1},{x:2},{x:4}];

arr.reduce(function (a, b) {
  return {x: a.x + b.x}; // returns object with property x
})

// ES6
arr.reduce((a, b) => ({x: a.x + b.x}));

// -> {x: 7}

Example 2: reduce javascript

//note idx and sourceArray are optional
const sum = array.reduce((accumulator, element[, idx[, sourceArray]]) => {
	//arbitrary example of why idx might be needed
	return accumulator + idx * 2 + element 
}, 0);