How do you calculate simple interest in javascript?

Answer 1

You take the formula for simple interest, and create a function based off of it.

The formula to generate simple interest is:

Interest = Principal * Rate * Time

In this case "time" refers to the number of periods for which interest will be applied.

In most cases you're going to want to solve this equation for interest. So, you write a JavaScript function that will do the math for you. The function should take Principal, Rate, and Time as parameters, and return Interest.

function calculateSI ( p, r, t ){

//You want to check that p, r, and t are appropriate values and//types. I'll skip that here for brevityreturn p*r*t;

}

That's all there is to it. To call the function, you'd pass in values in the proper order, of define them in the call. Then you capture the returned value with a variable like so:

var simpleInterest = calculateSI ( 5000, 0.12, 64 );

//simpleInterest would now hold the value of "38400."

I've gone ahead and create a JSFiddle example for you in which I set up a form to deal with acquiring and displaying the values. That version also shows how to write a single function to solve for any of the missing variables. (See related link.)