Take User input to perform calculation in javascript

Question

I have written this piece of code but it is not working. I want to use the value entered by user to perform following calculation...

function calculateBasic()
		{
			var uservalue = form.size.value;
			var powerForOrganic = Math.pow(uservalue,1.05);
			var effortForOrganic = 2.4 * power;
			var powerTdevOrganic = Math.pow(effortForOrganic,0.38);
			var tdevForOrganic =  2.5 * powerTdevOrganic;
			var averageStaffForOrganic = effortForOrganic / tdevForOrganic;
			var productivityLevelForOrganic = averageStaffForOrganic / effortForOrganic;
			alert( "Effort :" + effortForOrganic + "TDEV :" + tdevForOrganic + "Average Staff :" + averageStaffForOrganic + "Productivity :" + productivityLevelForOrganic);
			
		}

<input type="text" id="size" placeholder="Enter the size in KLOC">
<input type="button" id="enterInfo" Value="Submit"  onclick="calculateBasic(this.form);">

Answer 1

Your line should be

var uservalue = document.getElementById("size").value;

power also wasn't defined. You probably meant powerForOrganic, which was defined the line before.

var effortForOrganic = 2.4 * powerForOrganic;

Here is the complete code

function calculateBasic() {
    var uservalue = Number(document.getElementById("size").value);
    var powerForOrganic = Number(Math.pow(uservalue,1.05));
    var effortForOrganic = Number(2.4 * powerForOrganic);
    var powerTdevOrganic = Number(Math.pow(effortForOrganic,0.38));
    var tdevForOrganic =  Number(2.5 * powerTdevOrganic);
    var averageStaffForOrganic = effortForOrganic / tdevForOrganic;
    var productivityLevelForOrganic = averageStaffForOrganic / effortForOrganic;
    alert( "Effort :" + effortForOrganic + "TDEV :" + tdevForOrganic + "Average Staff :" + averageStaffForOrganic + "Productivity :" + productivityLevelForOrganic);

    }

var button = document.getElementById("enterInfo");

button.addEventListener("click", function() {
    calculateBasic();
});

http://jsfiddle.net/739amacp/