Perform operations on button values in JavaScript - javascript

I'm trying to make a calculator in JS and I'm searching for ways to add, subtract, multiply and divide button values. I've created a function to display the buttons but now I realize that that might not be necessary and I might need just one function which displays and does the operation.
HTML code:
<div class="numbers">
<button value="1" onclick="displayButtons(this)">1</button>
<button value="2" onclick="displayButtons(this)">2</button>
<button value="3" onclick="displayButtons(this)">3</button>
<button value="4" onclick="displayButtons(this)">4</button>
<button value="=" id="calculate" onclick="performOperations(this)">=</button>
**etc.**
<div class="operations">
<button value="+" onclick="displayButtons(this)" style="width: 2rem; top: 5rem;">+</button>
<button value="-" onclick="displayButtons(this)" style="left: -6rem; top: 5rem;">-</button>
**etc.**
JS code:
function displayButtons(button) {
outputDiv.innerHTML += button.value
}
function performOperations(button) {
var val = parseFloat(button.getAttribute("value"));
var total = parseFloat(document.getElementById('output').getAttribute("value"));
document.getElementById('output').innerHTML = total + val;
}
That is my attempt to do addition the button values and I have the performOperations called on the "=" sign which currently displays NaN onclick. (I'm working on the addition first).
Any push in the right direction is appreciated. Thank you!

You're right that you can use one function to do all the work but it means that you have to mark up your HTML with classes and data-attributes.
In this example I've used CSS grid to display the various calculator buttons. The "equals" and "clear" buttons have a data attribute to help the function decide what operation to do.
// Cache our elements and add an event listener
// to the button container. `handleClick` returns a
// new function that is called when the listener is fired
const output = document.querySelector('.output');
const buttons = document.querySelector('.buttons');
buttons.addEventListener('click', handleClick(), false);
function handleClick() {
// Initialise the sum
const sum = [];
// Return the function that will be called
// when a click event occurs
return function(e) {
// Because we're using event delegation (details
// below) we need to check that the element that
// was clicked was a button
if (e.target.matches('.button')) {
// Destructure the type from the dataset, and
// the text content
const { dataset: { type }, textContent } = e.target;
// `switch` on the type
switch (type) {
// If it's equals evaluate the elements in
// the array, and output it
case 'equals': {
output.textContent = eval(sum.join(''));
break;
}
// Clear empties the array, and clears
// the output
case 'clear': {
sum.length = 0;
output.textContent = '';
break;
}
// Otherwise add the textContent to
// the array, and update the output
default: {
sum.push(textContent);
output.textContent = sum.join(' ');
break;
}
}
}
}
}
.container{width:175px;}
.buttons {display: grid; grid-template-columns: repeat(4, 40px);grid-gap:0.3em;}
.button {display:flex;justify-content:center;align-items:center;background-color: #efefef; border: 1px solid #565656;padding: 0.5em;}
.button:not(.void):hover {background-color: #dfdfdf; cursor:pointer;}
.output {height: 20px; padding: 0.5em 0.2em;font-size: 1.2em;border:1px solid #565656;margin-bottom: 0.2em;}
<div class="container">
<div class="output"></div>
<div class="buttons">
<div class="button">7</div>
<div class="button">8</div>
<div class="button">9</div>
<div class="button">*</div>
<div class="button">4</div>
<div class="button">5</div>
<div class="button">6</div>
<div class="button">/</div>
<div class="button">1</div>
<div class="button">2</div>
<div class="button">3</div>
<div class="button">-</div>
<div class="button">0</div>
<div data-type="clear" class="button">C</div>
<div data-type="equals" class="button">=</div>
<div class="button">+</div>
</div>
</div>
Additional documentation
Destructuring assignment
Event delegation

Related

Displaying how many times a button has been clicked

I have created a button in HTML and I want to know how I can use Vue.js to display in the console how many times it has been pressed at.
This is what I have done so far:
<div class="123">
<button id = "Abutton" #click="abutton()">
<img src="randomimage.png"
style="width: 30px; height: 30px;"
/>
</button>
</div>
And in Vue.js:
abutton: function (e) {
const ButtonVal = e.target.value;
console.log("Number of likes:" + ButtonVal)
},
A button has no value... But you could use a data attribute like this:
<div class="123">
<button id = "Abutton" #click="abutton()" data-clickcount="0">
<img src="randomimage.png"
style="width: 30px; height: 30px;"
/>
</button>
</div>
And in Vue.js:
abutton: function (e) {
// Get the count
const ButtonVal = +(e.target.dataset.clickcount);
// Increment and store it
e.target.dataset.clickcount = ButtonVal++;
// log it
console.log("Number of likes:" + ButtonVal)
},

jQuery .append() and .remove() skipping behavior with slider function

I'm having trouble with some dynamic HTML. I've got a slider that adds or removes DOM elements as the value changes. Each time it increases, an element is added, and each time it decreases, an element is removed.
Here's the HTML:
<input type="range" min="3" max="16" class="rgb-slider" value="3" tabindex="-1" oninput="slider(this.value)">
<div class="container">
<div class="boxes">
<div class="box"><span></span></div>
<div class="box"><span></span></div>
<div class="box"><span></span></div>
</div>
</div>
Here's the JS:
var colorCount = 3;
function slider(value) {
if (colorCount < parseInt(value)) {
$('.boxes').append('<div class="box"><span></span></div>');
colorCount = value;
} else {
$('.box:last-child').remove();
colorCount = value;
}
}
http://jsfiddle.net/meu9carx/
However, when I quickly move the slider, it seems to skip or trip up, and I end up with more or fewer than I started with. The slider has a range from 3-16, but sometimes the min value goes to more or less than 3. Sometimes, all the boxes vanish.
Is there a smarter way to code this? I'm trying to avoid hard-coding divs here.
If the mouse moves fast, it's possible for the input value to change by more than one (in either direction) during a single input event. Use the value in the input to determine how many squares there should be exactly, rather than adding or removing only a single element each time.
const boxes = $('.boxes');
$('input').on('input', function() {
const targetSquares = Number(this.value);
while (boxes.children().length < targetSquares) {
boxes.append('<div class="box"><span></span></div>');
}
while (boxes.children().length > targetSquares) {
$('.box:last-child').remove();
}
});
body{
background: #777;
font-family: 'Arimo', sans-serif;
}
.container { padding: 20px 0; }
.boxes { display: flex; }
.box {
padding: 10px;
background: #ffffff;
height: 100px;
flex: 1;
border: 1px solid black;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="range" min="3" max="16" class="rgb-slider" value="3" tabindex="-1">
<div class="container">
<div class="boxes">
<div class="box"><span></span></div>
<div class="box"><span></span></div>
<div class="box"><span></span></div>
</div>
</div>

Move button when clicked

How do I move the button from the div with id of two to the div with id of one when I click the button?
<div id="one">
</div>
<div id="two">
<button onclick="moveMe"></button>
</div>
function moveMe() {
// ??
}
We can do this using removeChild and appendChild js features. Provided an example below with working code.
const one = document.getElementById("one");
const two = document.getElementById("two");
const allButtons = document.getElementsByTagName("button");
for(let i = 0; i < allButtons.length; i++) {
const btn = allButtons[i];
btn.addEventListener("click", function(e) {
const el = e.currentTarget;
const newParent = el.parentNode.id == "one" ? two : one;
el.parentNode.removeChild(el);
newParent.appendChild(el)
});
}
.section {
height: 100px;
width: 150px;
padding: 4px;
margin: 5px;
float: left;
}
#one {
background: #CCC;
}
#two {
background: #eee;
}
button {
margin: 2px;
padding: 4px;
}
<h3>Toggle button between container on click</h3>
<div>
<div class="section" id="one"></div>
<div class="section" id="two"> <button>Move me 1</button> <button>Move me 2</button></div>
</div>
function moveMe() {
const divTwo = document.getElementById("two")
const divOne = document.getElementById("one")
const newButton = document.createElement("button")
newButton.innerText = "Click me"
divOne.appendChild(newButton)
divTwo.children[1].remove()
}
<div id="one">
<p>
div one
</p>
</div>
<div id="two">
<p>
div two
</p>
<button onclick="moveMe()">Click me</button>
</div>
You can try this:
// select the elements
const button = document.querySelector('button');
const firstDiv = document.getElementById('one');
// add eventListener
button.addEventListener('click', moveButton);
// move the button
function moveButton() {
firstDiv.append(button);
}
<div id="one">
</div>
<div id="two">
<button id="btn" onclick="moveMe">MoveMe</button>
</div>
function moveMe() {
var divOne = document.querySelector("#one");
var btn = document.querySelector("#btn");
divOne.appendChild(btn);
}
You can use code below to move the element.
There's some changes that I made on your code,
you can use version 1 or version 2
the changes on first version is i add "id" attribute on the element so we don't resort to use the tag only as selector, of course you can also use #two>button to make it more precise
the changes on second version is i add a parameter to your function this time it will handle the current element using "this" keyword when calling the function
function moveMe(){
// one.appendChild(document.querySelector("button"));
one.appendChild(move);
}
function moveMeV2(element){
one.appendChild(element);
}
<div id="one">
<span>one</span>
</div>
<div id="two">
<span>two</span>
<button id="move" onclick="moveMe()">Move Me</button>
<button onclick="moveMeV2(this)">Move Me V2</button>
</div>

JavaScript delete modal onclick and decrease counter

I want to make a basic inbox function. It contains 3 messages.
So I want to make that when the user click onto the DELETE button, set the msg1's display to none, and decrease the messages value.
Here is the example code:
var x = 2;
function deleteMsg1() {
var msg1 = document.getElementsByClassName("cont");
if (confirm("Are you sure to want to delete this message?")) {
msg1[0].style.display = "none";
x = x-1;
} else {
}
}
function deleteMsg2() {
var msg2 = document.getElementsByClassName("cont2");
if (confirm("Are you sure to want to delete this message?")) {
msg2[0].style.display = "none";
x = x-1;
} else {
}
}
document.getElementById("msgcount").innerHTML = x;
.cont, .cont2 {
background-color: red;
padding: 5px;
width: 100px;
margin: 25px 0;
}
.show {
display: block;
}
<h1>There are <span id="msgcount"></span>messages</h1>
<button onclick="deleteMsg1()">Delete</button>
<div class="cont">
Some text...
</div>
<br><br>
<button onclick="deleteMsg2()">Delete</button>
<div class="cont2">
Some text...
</div>
I know this isn’t the best idea, but I guess it’s bad.
I think I should do this with one function() and try something event listener but I don't really know how to do that.
Any idea or help?
You should wrap each message's HTML in a parent element so that you can then treat each set of elements that comprise a message as a single unit and delete it all at once.
To be able to do this with a single function, you can use this to reference the element that triggered the callback function in the first place and .closest() to access the single parent wrapper.
Notes:
Do not use inline HTML event attributes, like onclick.
Separate your HTML and your JavaScript and use .addEventListener()
to bind elements to event callbacks. Even MDN recommends not using
them.
Do not use .getElementsByClassName() as it is a 25+ year old
API that has significant performance implications. Instead, use the
modern .querySelectorAll() method.
Do not use .innerHTML if you can avoid it as it has security and
performance implications. Since the text you are wanting to update
doesn't have any HTML in it anyway, .innerHTML is not warranted.
Instead, use .textContent.
// Do your event binding in JavaScript, not HTML
document.querySelectorAll("button").forEach(function(element){
element.addEventListener("click", function(){
if (confirm("Are you sure to want to delete this message?")) {
// All you need to do is delete the nearest complete
// ancestor message construct, which can be done with
// the .closest() method
this.closest(".message").remove();
updateMessageCount();
}
});
});
function updateMessageCount(){
// Set the count equal to the length of the
// collection returned by searching for all the
// messages
document.getElementById("msgcount").textContent =
document.querySelectorAll(".message").length;
}
updateMessageCount();
.cont, .cont2 {
background-color: red;
padding: 5px;
width: 100px;
margin: 25px 0;
}
.show {
display: block;
}
<h1>There are <span id="msgcount"></span> messages</h1>
<!-- By wrapping each message, you can treat all its HTML
as one single unit. -->
<div class="message">
<button>Delete</button>
<div class="cont">
Some text...
</div>
</div>
<br><br>
<div class="message">
<button>Delete</button>
<div class="cont">
Some text...
</div>
</div>
Explained
Here's a simple enough solution, you need to update the HTML manually every time you want to update the value of x. That's why I created an updateX function, it'll just take the value & update the DOM, it's quite that simple.
const updateX = (x) => {
document.getElementById("msgcount").innerHTML = x;
};
let x = 2;
const del = (className) => {
const msg = document.getElementsByClassName(className);
if (confirm("Are you sure to want to delete this message?")) {
msg[0].style.display = "none";
x--;
} else {
console.log("===");
}
updateX(x);
};
updateX(x);
.cont,
.cont2 {
background-color: red;
padding: 5px;
width: 100px;
margin: 25px 0;
}
.show {
display: block;
}
<h1>There are <span id="msgcount"></span>messages</h1>
<button onclick="del('cont')">Delete</button>
<div class="cont">
Some text...
</div>
<br/><br/>
<button onclick="del('cont2')">Delete</button>
<div class="cont2">
Some text...
</div>
My advice to you: Never declare events js inside html structure tags! As here:
<button onclick="deleteMsg1()">Delete</button>
This is a very bad practice. This has many disadvantages. And this can lead to bad consequences.
I made a solution for you with the forEach() method, without using javascript in html.
The Delete button is also removed.
let msg = document.querySelectorAll(".cont");
let btn_del = document.querySelectorAll('.btn_del');
let x = 2;
btn_del.forEach(function (btn_del_current, index) {
btn_del_current.addEventListener('click', function () {
if (confirm("Are you sure to want to delete this message?")) {
this.style.display = "none";
msg[index].style.display = "none";
x = x - 1;
document.getElementById("msgcount").innerHTML = x;
} else {}
});
});
.cont, .cont2 {
background-color: red;
padding: 5px;
width: 100px;
margin: 25px 0;
}
.show {
display: block;
}
<h1>There are <span id="msgcount"></span>messages</h1>
<button class="btn_del">Delete</button>
<div class="cont">
Some text...
</div>
<br><br>
<button class="btn_del">Delete</button>
<div class="cont">
Some text...
</div>

How do I count divs clicked using an event listener in javascript

I'm trying the count the total number of divs clicked and exactly which ones were clicked. I'm using an event listener because the onclick is already used. Let me clarify a bit more, first, here's my code:
<div class="wrapper">
<div class="square" onclick="classList.toggle('selected')">1</div>
<div class="square" onclick="classList.toggle('selected')">2</div>
<div class="square" onclick="classList.toggle('selected')">3</div>
</div>
<div id="dis"></div>
.selected {
background: white;
}
var numClicked = document.querySelectorAll('.wrapper');
numClicked.forEach(numClicked =>
numClicked.addEventListener('click', clickedDivs)
)
function clickedDivs () {
i = 0;
numClicked.forEach(numClicked =>
i++
var x = document.getElementById("dis");
x.innerHTML = "Squares selected: " + i;
}
What I'm trying to do with my javascript is count how many divs are selected. I'm also trying to tell exactly where ones were clicked. Let's say 1 and 2 were clicked, how do I find those were clicked and total number of divs clicked using js?
What you are doing wrong here is:
You are initialising i within the onClick event fn. which will always reset the value to 0 when ever the div will be clicked.
you are not storing anywhere which div is clicked
You are adding you'r listener on wrapper instead of .square (if you are not trying to get the value of clicked wrappers instead of clicked square)
So you can modify you'r javascript like this
<style>
.square{width: 100px; height: 100px; background: grey;}
.selected {
background: white;
}
</style>
<div class="wrapper">
<div class="square" onclick="classList.toggle('selected')">1</div>
<div class="square" onclick="classList.toggle('selected')">2</div>
<div class="square" onclick="classList.toggle('selected')">3</div>
</div>
<div id="dis"></div>
<script>
var numClicked = document.querySelectorAll('.square');
numClicked.forEach(numClick => {
numClick.addEventListener('click', clickedDivs)
}
)
var itemsClicked = [] //to store which div is clicked
function clickedDivs (e) {
var value = e.target.innerHTML;
//edit
if(itemsClicked.indexOf(value) != -1) itemsClicked.splice(itemsClicked.indexOf(value), 1)
else
itemsClicked.push(value);
var x = document.getElementById("dis");
x.innerHTML = "Squares selected: " + itemsClicked.join(",");
}
</script>
edit:
added to code to remove data from the list if already exist.
Rather than attach a handler to each div, you can use 1 window event listener. Give each clickable div an id that contains "clickable" so the event listener can filter out divs you aren't tracking. When you first click a tracked div, set its id as a key within a global object and assign 1 as the value; on additional clicks, increase value by 1.
const clicks = {};
window.addEventListener("click", (e)=> {
const id = e.target.id;
if(!id.includes("clickable"))return;
clicks[id]? clicks[id] += 1 : clicks[id] = 1;
console.log(clicks);
},)
<div class="wrapper">
<div id="clickable1" class="square">1</div>
<div id="clickable2" class="square">2</div>
<div id="clickable3" class="square">3</div>
</div>
My solution, I haven't tested it yet, test it and tell me how we adjusted it.
<div class="wrapper">
<div class="square" id="d-1">1</div>
<div class="square" id="d-2">2</div>
<div class="square" id="d-3">3</div>
</div>
<div id="result"></div>
var count = [];
var wrappers = document.querySelectorAll('.wrapper');
wrappers.forEach(square => square.addEventListener('click',() => onClickwrapperSquare(square.id));
function onClickwrapperSquare(id) {
var result = document.getElementById('result');
if(count.indexOf(id) == -1){
count.push(id);
}else{
count = count.slice(count.indexOf(id)+ 1);
}
result.innerHTML = `Squares selected: ${count.length}`;
}
This can be simply achieved by jQuery.
var count;
$(".square").click(function (){
count = count+1;
$("#dis").html(count);
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="wrapper">
<div class=square">1</div>
<div class="square">2</div>
<div class="square">3</div>
</div>
<div id="dis"></div>

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