Welcome Learner today in this blog post we will be Build a Loan Finance Calculator Using Time, Interest, and Amount in Browser Using Javascript CSS3 and HTML5.

Let’s start

calculators_financial_loan-calculator

 

Mortgage Loan Calculator

Bank loan/mortgage Interest Rates Calculator

 

All the Complete source code of the application is shown Down.

In order to lets started, you need to make a file index.html and copy-paste the mentioned code

index.html 

 

<!doctype html>
<html lang="en">
  <head>
    <title>Loan Calculator</title>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
  </head>
  <body class="bg-dark">
    <div class="container">
      <div class="row">
        <div class="col-md-6 mx-auto">
          <div class="card card-body text-center mt-5">
            <h1 class="heading display-5 pb-3">Loan Calculator</h1>
            <form id="loan-form">
              <div class="form-group">
                <div class="input-group">
                  <span class="input-group-addon">$</span>
                  <input type="number" class="form-control" id="amount" placeholder="Loan Amount">
                </div>
              </div>
              <div class="form-group">
                <div class="input-group">
                  <span class="input-group-addon">%</span>
                  <input type="number" class="form-control" id="interest" placeholder="Interest">
                </div>
              </div>
              <div class="form-group">
                <input type="number" class="form-control" id="years" placeholder="Years To Repay">
              </div>
              <div class="form-group">
                <input type="submit" value="Calculate" class="btn btn-dark btn-block">
              </div>

              
            </form>
            <!-- LOADER -->
            <!--
            <div id="loading">
              <img src="img/loading.gif" alt="">
            </div>
            -->
            <!-- RESULTS -->
            <div id="results" class="pt-4">
              <h5>Results</h5>
              <div class="form-group">
                <div class="input-group">
                  <span class="input-group-addon">Monthly Payment</span>
                  <input type="number" class="form-control" id="monthly-payment" disabled>
                </div>
              </div>

              <div class="form-group">
                <div class="input-group">
                  <span class="input-group-addon">Total Payment</span>
                  <input type="number" class="form-control" id="total-payment" disabled>
                </div>
              </div>

              <div class="form-group">
                <div class="input-group">
                  <span class="input-group-addon">Total Interest</span>
                  <input type="number" class="form-control" id="total-interest" disabled>
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>

    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
    <script src="app.js"></script>
  </body>
</html>

 

 

script.js 

 

 

// Listen for submit
document.getElementById('loan-form').addEventListener('submit', calculateResults);

// Calculate Results
function calculateResults(e){

// console.log("calculating");

// Declare UI Variables

const amount = document.getElementById('amount');
const interest = document.getElementById('interest');
const years = document.getElementById('years');
const monthlyPayment = document.getElementById('monthly-payment');
const totalPayment = document.getElementById('total-payment');
const totalInterest = document.getElementById('total-interest');

// Turn amount into decimal and store it into variable
const principal = parseFloat(amount.value);
const calculatedInterest = parseFloat(interest.value) /100 / 12;
const calculatedPayment =  parseFloat(years.value) * 12;

// Compute monthly payments
const x = Math.pow(1 + calculatedInterest, calculatedPayment);
const monthly = (principal * x * calculatedInterest)/(x-1);


// Check if value is finite

if(isFinite(monthly)){
	monthlyPayment.value = monthly.toFixed(2);
	totalPayment.value = (monthly * calculatedPayment).toFixed(2);
	totalInterest.value = ((monthly * calculatedPayment) - principal).toFixed(2);

} else{
	showError("Please check your numbers")
}

e.preventDefault();
}

// Function to show error
function showError(error){
	// create div
	const errorDiv = document.createElement('div');

	// Get card and heading in order to add new div to DOM. Parent element
	const card = document.querySelector('.card');
	const heading = document.querySelector('.heading');


	// Give div a class name
	errorDiv.className = 'alert alert-danger';

	// Create text and append div
	errorDiv.appendChild(document.createTextNode(error));

	// Insert error above heading. Insert above will take in the parent element which is the card in this case and for the parameters
	// It will take in the element you want to put in and the element you want to put it before, in this case errorDiv and the heading

	card.insertBefore(errorDiv, heading);

	// Clear error after 3 seconds

	setTimeout(clearError, 3000);

}


// Create clear error
function clearError(){
	document.querySelector('.alert').remove();
}

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