The cart total variable in Vuejs is coming back as NaN

Question

The cart total variable in Vuejs is coming back as NaN

I'm currently in the process of creating a cart system using vuejs and I've encountered an issue where my total variable is displaying NaN instead of calculating the total price of all products.

Below is the function responsible for calculating the total

total: function(){
    var totalPrice = 0;
    for (var item in this.products){
        totalPrice += item.price;
    }
    return totalPrice;
}

Next, here's how I have it set up in my template for display

Total Price: ${{total}}

javascript vue.js

Answer 1

Answer №1

When using a <strong>for in</strong> loop, keep in mind that it is meant for looping through object properties, not arrays. To learn more about this, visit <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in" rel="nofollow noreferrer">this link</a>.</p>

<p>If you try to loop through an array using <strong>for in</strong>, you will get the index of the product instead of the product itself. This means that when you execute <code>tot += product.price;

, you are essentially adding 0 (the initial value of tot) and undefined, resulting in NaN.

To properly loop through arrays, consider using the .forEach method like so:

total: function(){
  let tot = 0;
  this.products.forEach(product => tot += product.price)
  return tot;
}

Alternatively, you can utilize the reduce method instead of forEach():

total: function(){
  return this.products.reduce((tot, product) => tot += product.price, 0)
}

Answer 2

When using a <strong>for in</strong> loop, keep in mind that it is meant for looping through object properties, not arrays. To learn more about this, visit <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in" rel="nofollow noreferrer">this link</a>.</p>

<p>If you try to loop through an array using <strong>for in</strong>, you will get the index of the product instead of the product itself. This means that when you execute <code>tot += product.price;

, you are essentially adding 0 (the initial value of tot) and undefined, resulting in NaN.

To properly loop through arrays, consider using the .forEach method like so:

total: function(){
  let tot = 0;
  this.products.forEach(product => tot += product.price)
  return tot;
}

Alternatively, you can utilize the reduce method instead of forEach():

total: function(){
  return this.products.reduce((tot, product) => tot += product.price, 0)
}

Answer 3

Answer №2

If you want to tackle the issue yourself, why not try debugging it by following this code snippet:

  for ( var product in this.products){
    console.log(product);
    tot += product.price;
}

Upon running this snippet, you will realize that product is actually an enumerable property of this.products. In case this.products is an Array, the output will be 0, 1, 2, and so on. For a better understanding of how for..in works, check out the link provided.

Therefore, if you are determined to use for..in, it's recommended to make the following adjustment:

tot += this.products[product].price;

Alternatively, you can opt for a more efficient solution using reduce to sum up the values:

tot: function (){
    var tot = 0;
    tot = this.products.reduce((pre, next) => {
        return pre += next.price;
    }, tot);
    return tot;
}

Answer 4

If you want to tackle the issue yourself, why not try debugging it by following this code snippet:

  for ( var product in this.products){
    console.log(product);
    tot += product.price;
}

Upon running this snippet, you will realize that product is actually an enumerable property of this.products. In case this.products is an Array, the output will be 0, 1, 2, and so on. For a better understanding of how for..in works, check out the link provided.

Therefore, if you are determined to use for..in, it's recommended to make the following adjustment:

tot += this.products[product].price;

Alternatively, you can opt for a more efficient solution using reduce to sum up the values:

tot: function (){
    var tot = 0;
    tot = this.products.reduce((pre, next) => {
        return pre += next.price;
    }, tot);
    return tot;
}

Answer 5

Answer №3

In the event that the previous solutions are ineffective, consider modifying the return statement to read as follows:

return total || 0

Answer 6

In the event that the previous solutions are ineffective, consider modifying the return statement to read as follows:

return total || 0

The cart total variable in Vuejs is coming back as NaN

Answer №1

Answer №2

Answer №3

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