is a simple web calculator, which, as the title suggests, performs interest-related calculations. Currently it offers four options for calculation: simple interest, compound interest, annuities (wherein money is deposited and compounded periodically), and a loan calculator (with the option to specify any percentage down, to simulate a mortgage).
The website uses Flask as a web server and uses Bootstrap elements in its user interface.Clicking on each of the four options—simple and compound interest, annuity, and loan/mortgage—via a navbar brings the viewer to a form where they can specify the details of their calculation. If the calculate button is pressed and the values are confirmed to be valid, the form's values are fed into a function in application.py that gives out the results and formats them as currency. The formulae for compound interest, annuities and mortgages is well-documented. These results are presented in a new page.
The extra "touch" that distinguishes this calculator from any other is that it also provides a chart graphic where users can make sense of the data. This is done using some Flask trickery and the Chartist.js library. For instance, in calculating an annuity, the number of total deposits is calculated. For each deposit, one list stores how much money has been totally deposited, while another stores the total interest at that point. These lists are then passed as arguments when the HTML is rendered into the JS function that creates the chart. The result is a scrollable bar chart, where each bar displays the total balance of the annuity at a certain deposit time, as well as how much of that balance is money from deposits and money from interest. The same idea applies to the other calculation options—e.g. for the "loan/mortgage" option, the chart displays how much of each payment goes toward paying off interest and paying off the principal for each payment. Some jQuery also displays a tooltip that shows the value of each bar when the mouse hovers over it.
Creating this project helped me get moreo comfortable with Bootstrap and also JS (especially with using libraries), ultimately helping me brighten up a run-of-the-mill calculator with responsive and dynamically-generated charts that help illustrate numbers in a graphical and interactive format.