130 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
		
		
			
		
	
	
			130 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
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								title: Tip Calculator
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								---
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								## Tip Calculator
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								A Tip Calculator is a calculator that calculates a tip based on the percentage of the total bill.
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								## Step 1 - HTML: 
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								We create a form in order to enter the preferred amount:
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								```html
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								<!doctype html>
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								<html lang="en">
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								  <head>
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								    <title>Tip Calculator</title>
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								    <!-- Required meta tags -->
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								    <meta charset="utf-8">
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								    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
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								    <!-- Bootstrap CSS -->
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								    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
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								  </head>
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								  <body class="bg-dark">
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								    <div class="container">
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								      <div class="row">
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								        <div class="col-md-6 mx-auto">
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								          <div class="card card-body text-center mt-5">
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								            <h1 class="heading display-5 pb-3">Tip Calculator</h1>
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								            <form id="tip-form">
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								              <div class="form-group">
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								                <div class="input-group">
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								                  <span class="input-group-addon">$</span>
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								                  <input type="number" class="form-control" id="billTotal" placeholder="Total Bill">
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								                </div>
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								              </div>
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								              <div class="form-group tipPersent">
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								                <div class="input-group">
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								                  <label for="">Tip:</label>
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								                  <input type="range" class="form-control" id="tipInput" value="0">
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								                  <span class="input-group-addon" id="tipOutput"></span>
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								                </div>
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								              </div>
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								            </form>
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								            <hr>
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								            <!-- RESULTS -->
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								            <div id="results" class="pt-4">
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								              <h5>Results</h5>
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								              <div class="form-group">
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								                <div class="input-group">
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								                  <span class="input-group-addon">Tip amount</span>
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								                  <input type="number" class="form-control" id="tipAmount" disabled>
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								                </div>
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								              </div>
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								              <div class="form-group">
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								                <div class="input-group">
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								                  <span class="input-group-addon">Total Bill with Tip</span>
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								                  <input type="number" class="form-control" id="totalBillWithTip" disabled>
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								                </div>
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								              </div>
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								            </div>
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								          </div>
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								        </div>
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								      </div>
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								    </div>
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								    <!-- Optional JavaScript -->
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								    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
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								    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
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								    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
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								    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
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								  </body>
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								</html>
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								```
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								## Step 2 - CSS:
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								You design the style however you want. You can also use CSS to hide the results and show them through JavaScript after the user fills in the form:
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								```css
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								  #results {
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								         display:none;
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								       }
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								```
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								## Step 3: JavaScript: 
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								We add onchange event. The onchange event occurs when user interacts with the form. 
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								This action will execute a function that computes the final bill amount based on the percentage tip, then returns the results.
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								```javascript
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								document.querySelector('#tip-form').onchange = function(){
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								  var bill = Number(document.getElementById('billTotal').value);
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								  var tip = document.getElementById('tipInput').value;
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								  document.getElementById('tipOutput').innerHTML = `${tip}%`;
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								  var tipValue = bill * (tip/100)
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								  var finalBill = bill + tipValue
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								console.log(finalBill)
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								var tipAmount = document.querySelector('#tipAmount')
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								var totalBillWithTip = document.querySelector('#totalBillWithTip')
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								tipAmount.value = tipValue.toFixed(2);
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								 totalBillWithTip.value =finalBill.toFixed(2);
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								 //Show Results
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								  document.getElementById('results').style.display='block'
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								}
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								```
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								You can see a working example and its code on [Codepen.io](https://codepen.io/voula12/pen/djrZGw).
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