如何.filter和.reduce javascript数组对象

Question

WebDev Student. I am having an issue with using .filter + .reduce array methods and chaining to return the total cost of both items. Codeburst.io on the subject is super helpful but I need direction on how to apply to this specific exercise as I am targeting a property: value in the array.

This is an exercise in reducing the amount of code., so rather than using a for loop to iterate through an array, I need to apply a method(s) to .filter through and .reduce to return the total cost of each item in the array. .price

Using the shopCart variable, create a function that takes the shopCart variable and returns the total cost of both items as the total variable. Add Code after "// code below".

 var shopCart = [ { id: 0, name: 'Womens Shirt', price: 30, size: 'Small' }, { id: 1, name: 'childs shirt', price: 12, size: 'Large' } ] function getCost(items){ let total = 0; // code below // code above return total; } getCost(shopCart) < --- Add let cost = getCost(shopCart); < ---OMIT console.log(cost); < -- OMIT 

PLease re-review - Code has been amended.

Answer 1

Here's a more explicit approach.

function sum(nums) {
  return nums.reduce((a, b) => a + b)
}

const prices = items.map(item => item.price)
const total = sum(prices)

Answer 2

You can do this using iteration – for example, a for loop. In the getCost function, we have a total variable with an initial value of zero. Then for each element in the items array, the price is used to accumulate the total. However, this functionality is similarly available using the reduce method .

 var shopCart = [ { id: 0, name: 'Womens Shirt', price: 30, size: 'Small' }, { id: 1, name: 'childs shirt', price: 12, size: 'Large' } ]; function getCost(items) { var total = 0; items.forEach(e => total += e.price); return total; } let cost = getCost(shopCart); // 42 let costWithReduce = shopCart.reduce((a, c) => a + c.price, 0); // 42 console.log(cost, costWithReduce); 

Answer 3

You can use array#reduce . In a total accumulator, you can add price of each object.

 var shopCart = [{id: 0,name: 'Womens Shirt',price: 30,size: 'Small'},{id: 1,name: 'childs shirt',price: 12,size: 'Large'}]; function getCost(items){ return items.reduce(function(total, obj){ return total + obj.price; }, 0); } let cost = getCost(shopCart); console.log(cost); 

 var shopCart = [{id: 0,name: 'Womens Shirt',price: 30,size: 'Small'},{id: 1,name: 'childs shirt',price: 12,size: 'Large'}]; function getCost(items){ return items.reduce((total, {price}) => total + price, 0); } let cost = getCost(shopCart); console.log(cost); 

Answer 4

Answer same as others really, but within the required parameters.

 var shopCart = [ { id: 0, name: 'Womens Shirt', price: 30, size: 'Small' }, { id: 1, name: 'childs shirt', price: 12, size: 'Large' } ] function getCost(items){ let total = 0; // code below total = items.reduce((sum, item) => sum + item.price, total); // code above return total; } let cost = getCost(shopCart); console.log(cost);