创建一个处理Javascript中的对象数组的函数

Question

So I have an array of objects that looks like:

list = [firstObject {name: 'a', price: 0.5, quantity: 5, total: 2.5},
        secondObject {name: 'b', price: 2, quantity: 2, total: 4},
        thirdObject {name: 'd', price: 2, quantity: 1, total: 2}]

I'm trying to write a function that would allow me to print something like

• 5 a's costs $2.5
• 2 b's costs $4

• 1 c costs $2

• The total was $8.50

So far I have something like

let summary = (name, quantity, total) => {
 let item = list.name;
 let amount = list.quantity;
 let cost = list.total;
  return (`${amount} ${item} costs ${cost}`);
};

But it obviously doesn't work. I guess I'm a little confused as to how to go about how to properly access the values in those objects with my function. Any input would be greatly appreciated!

Answer 1

You want to do something like this

list = [{name: 'a', price: 0.5, quantity: 5, total: 2.5},
        {name: 'b', price: 2, quantity: 2, total: 4},
        {name: 'd', price: 2, quantity: 1, total: 2}];

function sum(list){
   let total = 0;

   list.forEach((item)=>{
      console.log(item.quantity + ' ' + item.name + ' costs ' + (item.price * item.quantity));
       total += item.price * item.quantity;
   }
   return total;
});
console.log('Total: ' + sum(list));

Answer 2

Try this snippt

<script>
let summary = (name, quantity, total) => {
    let item = name;
    let amount = quantity;
    let cost = total;
    return (`${amount} ${item} costs ${cost}`);
};
var list = [firstObject = {name: 'a', price: 0.5, quantity: 5, total: 2.5},
           secondObject = {name: 'b', price: 2, quantity: 2, total: 4},
           thirdObject = {name: 'd', price: 2, quantity: 1, total: 2}];

for (var item = 0; item < list.length; item++) {
    summary(list[item].name, list[item].quantity, list[item].total);
}
</script>

Answer 3

Your function can be made to work to return the string for one entry, not for list , so you should change that variable reference. You could use destructuring in the function parameter so you don't need any other variables or property references.

Then you need to call that function for each element in list . This you can do with map , which will give you an array of strings. Finally, join that array into one string:

 const list = [{name: 'a', price: 0.5, quantity: 5, total: 2.5}, {name: 'b', price: 2, quantity: 2, total: 4}, {name: 'd', price: 2, quantity: 1, total: 2}]; const summary = ({name, quantity, total}) => `${quantity} ${name}'s cost $${total}`; const output = list.map(summary).join('\\n'); console.log(output); // Code to display the total: const total = list.reduce((sum, {total}) => sum + total, 0); console.log(`The total is $${total}`); 

Answer 4

list = [{name: 'a', price: 0.5, quantity: 5, total: 2.5},
    {name: 'b', price: 2, quantity: 2, total: 4},
    {name: 'd', price: 2, quantity: 1, total: 2}]

function display (obj) {
    console.log(obj.quantity + " " + obj.name +  "'s costs $" + obj.total);
};

let total = 0;
list.forEach(function(obj) {
    display(obj);
    total += obj.total;
});

console.log("The total was ", total);

Answer 5

Here is the Classic

( you will first need to fix the array of objects declaration here...)

list = 
[
   { name: 'a', price: 0.5, quantity: 5, total: 2.5 },
   { name: 'b', price: 2, quantity: 2, total: 4 },
   { name: 'c', price: 2, quantity: 1, total: 2 }
];

Then you can move on to the task

var total = 0;
 for( var item in list )console.log(
       list[ item ].quantity + " " + list[ item ].name + "\'s cost $" + list[item].total
    ), total += list[ item ].total;
console.log( "The total was $"+ total );