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wejrowski/calculator.html

Last active March 14, 2021 18:59
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Web component + shadow DOM
Raw
calculator.html
<!DOCTYPE html>
<html>
<head>
<title>Calculator</title>
</head>
<body>
<basic-calculator></basic-calculator>
<template id="basicCalcTemplate">
<style>
:host {
border-radius: 7px;
overflow: hidden;
font-family: Helvetica, monospace, sans-serif;
font-size: 22px;
font-weight: 300;
margin: 0px;
background: #888;
border: 1px solid #888;
display: block;
width: 208px;
margin: 0 auto;
}
#stash {
border: 1px solid #ddd;
color: #888;
}
#output {
background: transparent;
border: 0;
color: white;
font-size: 40px;
font-weight: 200;
margin: 7% 10%;
text-align: right;
width: 80%;
}
.buttons {
display: flex;
flex-wrap: wrap;
}
.btn {
width: 50px;
height: 50px;
cursor: pointer;
line-height: 50px;
text-align: center;
display: inline-block;
background: #ddd;
margin: 1px;
}
.btn.btn--active { /* (1) .btn--active.btn--active (2) .btn.btn--active (3) move it. */
background: #bbb;
}
.btn--operator, .btn--calculate{
background: orange;
color: white;
}
.btn--special {
background: #ccc;
}
.btn--zero {
flex: 2;
}
</style>
<input id="output" value="0"></input>
<input type="hidden" id="stash"></input>
<input type="hidden" id="selectedFunction"></input>
<div class="buttons">
<div class="btn btn--special btn--clear">C</div>
<div class="btn btn--special btn--makeNegative">&plusmn;</div>
<div class="btn btn--special btn--percentage">%</div>
<div class="btn btn--operator" data-operator="/">&#247;</div>
<div class="btn btn--number">7</div>
<div class="btn btn--number">8</div>
<div class="btn btn--number">9</div>
<div class="btn btn--operator" data-operator="*">*</div>
<div class="btn btn--number">4</div>
<div class="btn btn--number">5</div>
<div class="btn btn--number">6</div>
<div class="btn btn--operator" data-operator="-">-</div>
<div class="btn btn--number">1</div>
<div class="btn btn--number">2</div>
<div class="btn btn--number">3</div>
<div class="btn btn--operator" data-operator="+">+</div>
<div class="btn btn--number btn--zero">0</div>
<div class="btn btn--decimal">.</div>
<div class="btn btn--calculate">=</div>
</div>
</template>
<script>
(function() {
'use strict';
var basicCalculatorPrototype = Object.create(HTMLElement.prototype);
basicCalculatorPrototype.is = "basic-calculator";
basicCalculatorPrototype.attachedCallback = function() {
console.log('attached', basicCalculatorPrototype.is);
var shadowRoot = this.attachShadow({ mode: 'closed' });
var templateClone = document.importNode(document.querySelector('#basicCalcTemplate').content, true);
shadowRoot.appendChild(templateClone);
var currentOperator = shadowRoot.querySelector('#selectedFunction'),
displayNumber = shadowRoot.querySelector('#output'),
stashedNumber = shadowRoot.querySelector('#stash');
var justPressedFunction = false;
var clearActiveButtonState = function() {
Array.prototype.forEach.call(shadowRoot.querySelectorAll('.btn--operator'), function(functionButton) {
functionButton.classList.remove('btn--active');
});
};
var lastPressed;// NUMBER, OPERATOR, CALCULATE, OTHER
var onPressClear = function() {
currentOperator.value = stashedNumber.value = "";
displayNumber.value = "0";
clearActiveButtonState();
lastPressed = "OTHER";
};
var onPressDecimal = function() {
if (lastPressed !== "OPERATOR" && this.innerHTML === "." && /\./.test(displayNumber.value)) {
return;
}
displayNumber.value = displayNumber.value + ".";
lastPressed = "NUMBER";
};
var onPressNegative = function() {
displayNumber.value = parseFloat(displayNumber.value) * -1;
clearActiveButtonState();
lastPressed = "OTHER";
};
var onPressPercentage = function() {
displayNumber.value = parseFloat(displayNumber.value) * 0.01;
clearActiveButtonState();
lastPressed = "OTHER";
};
var justPressedNumber = false;
var onPressNumber = function(e) {
var pressedNumber = e.currentTarget.innerHTML;
if (["OPERATOR", "CALCULATE"].includes(lastPressed)) {
justPressedFunction = false;
displayNumber.value = "";
}
if (lastPressed === "CALCULATE") {
stashedNumber.value = "";
}
if (displayNumber.value === "0") {
displayNumber.value = pressedNumber;
return;
}
justPressedNumber = true;
displayNumber.value = displayNumber.value + pressedNumber;
lastPressed = "NUMBER";
};
var justCalculated = false;
var calculate = function() {
var expression;
if (lastPressed !== "CALCULATE") {
expression = stashedNumber.value + currentOperator.value + displayNumber.value;
stashedNumber.value = displayNumber.value;
justCalculated = true;
} else {
expression = displayNumber.value + currentOperator.value + stashedNumber.value;
}
displayNumber.value = eval(expression);
clearActiveButtonState();
lastPressed = "CALCULATE";
};
var onPressOperator = function(e) {
// TODO: make awaitingCalculation()?
if (lastPressed === "NUMBER" && stashedNumber.value !=="") {
calculate();
}
justPressedFunction = true;
stashedNumber.value = displayNumber.value;
currentOperator.value = e.currentTarget.dataset.operator;
clearActiveButtonState();
e.currentTarget.classList.add('btn--active');
lastPressed = "OPERATOR";
};
Array.prototype.forEach.call(shadowRoot.querySelectorAll('.btn--number'), function(numberButton) {
numberButton.addEventListener('click', onPressNumber);
});
Array.prototype.forEach.call(shadowRoot.querySelectorAll('.btn--operator'), function(operatorButton) {
operatorButton.addEventListener('click', onPressOperator);
});
shadowRoot.querySelector('.btn--clear').addEventListener('click', onPressClear);
shadowRoot.querySelector('.btn--calculate').addEventListener('click', calculate);
shadowRoot.querySelector('.btn--makeNegative').addEventListener('click', onPressNegative);
shadowRoot.querySelector('.btn--percentage').addEventListener('click', onPressPercentage);
shadowRoot.querySelector('.btn--decimal').addEventListener('click', onPressDecimal);
Array.prototype.forEach.call(shadowRoot.querySelectorAll('.btn:not(.btn--calculate)'), function(button) {
button.addEventListener('click', function() {
justCalculated = false;
});
});
Array.prototype.forEach.call(shadowRoot.querySelectorAll('.btn:not(.btn--number)'), function(button) {
button.addEventListener('click', function() {
justPressedNumber = false;
});
});
};
document.registerElement(basicCalculatorPrototype.is, { prototype: basicCalculatorPrototype });
}());
</script>
</body>
</html>
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