// JavaScript Document

function isBlank(varString) {

var boolStringIsBlank = true

        var intI

        if(varString) {

                for(intI=0; intI < varString.length; intI++) {

                        if(varString.charAt(intI) != " ") {

                                boolStringIsBlank = false

                                break

                        }

                }

        }

        return boolStringIsBlank

}

function doCalc() {

        var boolPerform = true

        var strMsg

        var intDepth

        var intArea

        var sngResult

        if(isBlank(document.MulchCalc.thickness.value)) {

                boolPerform = false

                strMsg = "Thickness is required."

                document.MulchCalc.thickness.focus()

        }

        if(boolPerform)

                if(isBlank(document.MulchCalc.area.value)) {

                        boolPerform = false

                        strMsg = "Total Area is required."

                        document.MulchCalc.area.focus()
						
                }

        if(boolPerform) {

                intDepth = document.MulchCalc.thickness.value

				intArea = document.MulchCalc.area.value

                // The following comments relate to the calculation that follows them:

                // Multiply area by 144 to convert to square inches.

                // Assume 46656 cubic inches to the cubic yard...

                //      27 cubic feet per cubic yard

                //      x 1728 cubic inches per cubic foot

                //      = 46656 cubic inches per cubic yard

                // Before rounding, multiply by 100 (144 becomes 14400) to preserve 2 decimal positions.

                // After rounding, divide by 100 to restore the 2 decimal positions.

                sngResult = Math.round((intDepth * intArea * 14400) / 46656) / 100

                document.MulchCalc.Total.value = sngResult
        }
		
        else
                alert(strMsg)
}