Nandakumar Edamana
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Section: web-development

Simple Interest Calculator in JavaScript

Let us create a simple web app that helps to calculate simple interest. The code is given below. You can paste it into a text editor (e.g.: gEdit or Notepad), save it with a filename that has the extension .html (e.g.: simpleint.html), open it in a web browser, and run it.

	<title>Web App for Simple Interest Calculation</title>

            function calculate()
                p = document.getElementById("p").value;
                n = document.getElementById("n").value;
                r = document.getElementById("r").value;
                result = document.getElementById("result");
                result.innerHTML = "The interest is " + (p*n*r/100);

        <h1>Simple Interest Calculation</h1>

        Amount: <input id="p"><br/>
        Rate: <input id="r"><br/>
        No. of Years: <input id="n"><br/>

        <button onclick="calculate()">Calculate</button>

        <p id="result"></p>

The calculate() function acts as the handler for the onclick event of the button. That is, when the user clicks the button Calculate, the calculate() function is executed.

The function should get the values that the user has entered into the input boxes. In order to do this, it uses the document.getElementById() method and the value property. After the calculation, the result is put inside a paragraph element using the same mechanism (assignment instead of reading, this time).

Here it works:

Simple Interest Calculation

No. of Years:

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