So basically I am making an online restaurant website where you can order food. I am going to make cards for each food item listed. Right now, I am making buttons that add and subtract the number of each item the customer wants to purchase.
var counter = document.querySelector(".count");
var currentNumber = 0;
var classicBurger = 5.18;
var bargeBurger = 6.13;
function addOne(price) {
currentNumber += 1;
counter.innerHTML = currentNumber;
document.querySelector(".total-price").innerHTML =
"$" + (price * currentNumber).toFixed(2);
}
function subtractOne(price) {
if (currentNumber > 0) {
currentNumber += -1;
counter.innerHTML = currentNumber;
document.querySelector(".total-price").innerHTML =
"$" + (price * currentNumber).toFixed(2);
} else {
counter.innerHTML = 0;
}
} <html>
<div class="food-item">
<h3 class="item-title">Classic Burger</h3>
<p class="item-description">
Classic beef patty with lettuce, tomato, and cheese.
</p>
<div class="add-subtract-items">
<button class="subtract-item" onclick="subtractOne(classicBurger)">
-
</button>
<span class="count">0</span>
<button class="add-item" onclick="addOne(classicBurger)">+</button>
</div>
<p class="total-price">$0.00</p>
</div>
<div class="food-item">
<h3 class="item-title">Barge Burger</h3>
<p class="item-description">
Classic beef patty with lettuce, tomato, and cheese.
</p>
<div class="add-subtract-items">
<button class="subtract-item" onclick="subtractOne(bargeBurger)">
-
</button>
<span class="count">0</span>
<button class="add-item" onclick="addOne(bargeBurger)">+</button>
</div>
<p class="total-price">$0.00</p>
</div>
<html/>How do I get the second button to effect the correct HTML rather than the total of the first item?
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Answer
The problem with your code is the point at which you declare your variables, as well as the means by which you select the elements:
// here we get the first element in the document:
var counter = document.querySelector(".count");
// we set the currentNumber (the 'count') variable to 0:
var currentNumber = 0;
/* ... */
function addOne(price) {
// regardless of which button, for which menu-item,
// is pressed we increase the count (but this variable
// is applied as the counter for *all* menu-items):
currentNumber += 1;
// here we're using the first '.count' element in the
// document (regardless of which menu-item we're
// trying to order, or remove from the order):
counter.innerHTML = currentNumber;
// and again, we're using the first element within the
// document (regardless of which menu-item the buttons
// relate to):
document.querySelector(".total-price").innerHTML =
"$" + (price * currentNumber).toFixed(2);
}
// the same is true, below, for the subtraction function
// which I've removed for brevity
Instead, we need to look at which <button> was pressed and from there find the correct menu-item to increment or decrement; so in the following code I’ve taken advantage of EventTarget.addEventListener() to pass a reference to the triggered Event to the function that is bound as the event-listener:
// declaring named functions using Arrow functions (since we're not using the
// 'this' variable).
// a named function to format the cost to two decimal places:
const formatCost = (cost) => {
return (Math.ceil(cost * 100) / 100).toFixed(2);
},
// the following functions take advantage of EventTarget.addEventListener()
// passing the event-object to the function that's bound as the event-listener:
addOne = (evt) => {
// from the event-object we first retrieve the 'evt.currentTarget', this
// is the element to which the event-listener was bound (in this case the
// <button class="add-item"> elements), from there we use Element.closest()
// to find the ancestor <div class="food-item"> element (effectively to find
// the first ancestor that wraps the <button> elements as well as the other
// elements we wish to use):
let cardParent = evt.currentTarget.closest('div.food-item'),
// from the cardParent we then use Element.querySelector() to select
// the first element within that Element (the cardParent) that matches
// the supplied CSS selector:
costElement = cardParent.querySelector('span.cost'),
countElement = cardParent.querySelector('span.count'),
// from those elements we determine the cost, using parseFloat()
// to convert the text-content of the element into a number we
// can work with:
cost = parseFloat(costElement.textContent),
// we update the current count by adding 1 to the number
// retrieved with parseInt():
count = parseInt(countElement.textContent) + 1;
// we then update the countElement to reflect the new - increased - count:
countElement.textContent = count;
// and we then find the '.total-price' element, and update its text-content
// to reflect the formatted cost:
cardParent.querySelector('.total-price').textContent = formatCost(cost * count);
},
subtractOne = (evt) => {
// here we do almost exactly as we did above:
let cardParent = evt.currentTarget.closest('div.food-item'),
costElement = cardParent.querySelector('span.cost'),
countElement = cardParent.querySelector('span.count'),
cost = parseFloat(costElement.textContent),
// obviously we don't (yet) adjust the count:
count = parseInt(countElement.textContent);
// because we first need to check that the count is greater than zero:
if (count > 0) {
// if so, we then subtract one from the count:
count = count - 1;
// we then update the countElement to reflec the new count:
countElement.textContent = count;
}
// and finally we update the '.total-price' element to reflect the new cost:
cardParent.querySelector('.total-price').textContent = formatCost(cost * count);
};
// here we select all elements in the document that match the supplied CSS selector, and
// use NodeList.forEach() to iterate over those elements, and:
document.querySelectorAll('button.subtract-item').forEach(
// we then bind the subtractOne() function (note the lack of parentheses)
// as the 'click' handler for the current element of the NodeList:
(subtraction) => subtraction.addEventListener('click', subtractOne)
);
// as above, but obviously we're binding the addOne() function
// to the 'button.add-item' elements:
document.querySelectorAll('button.add-item').forEach(
(addition) => addition.addEventListener('click', addOne)
);*,
::before,
::after {
box-sizing: border-box;
font: normal 400 1rem / 1.5 sans-serif;
margin: 0;
padding: 0;
}
body {
display: flex;
flex-wrap: wrap;
gap: 1em;
padding: 1em;
}
.food-item {
border: 1px solid #000;
border-radius: 1em;
padding: 0.5em;
}
h3 {
font-weight: 600;
}
.add-subtract-items {
align-content: center;
display: flex;
gap: 0.5em;
justify-content: center;
width: minmax(6em, 40%);
}
button,
span.count {
text-align: center;
}
button {
cursor: pointer;
width: 2em;
}
:is(.cost, .total-price)::before {
content: "$";
}<div class="food-item">
<h3 class="item-title">Classic Burger</h3>
<span class="cost">5.18</span>
<p class="item-description">
Classic beef patty with lettuce, tomato, and cheese.
</p>
<div class="add-subtract-items">
<button class="subtract-item">
-
</button>
<span class="count">0</span>
<button class="add-item">+</button>
</div>
<p class="total-price">0.00</p>
</div>
<div class="food-item">
<h3 class="item-title">Barge Burger</h3>
<span class="cost">6.13</span>
<p class="item-description">
Classic beef patty with lettuce, tomato, and cheese.
</p>
<div class="add-subtract-items">
<button class="subtract-item">
-
</button>
<span class="count">0</span>
<button class="add-item">+</button>
</div>
<p class="total-price">0.00</p>
</div>
<div class="food-item">
<h3 class="item-title">Milkshake</h3>
<span class="cost">4.35</span>
<p class="item-description">
Tastes like a five-dollar shake, for a little bit less.
</p>
<div class="add-subtract-items">
<button class="subtract-item">
-
</button>
<span class="count">0</span>
<button class="add-item">+</button>
</div>
<p class="total-price">0.00</p>
</div>References: