Creatinine Clearance Calculator Javascript Logic

cclr_calculator.js

// set up our units of conversions, could be shared between multiple calculators
var units = {
    "age": {"yr": 1, "mth": 12.0},
    "weight": {"kg": 1, "lb": 2.20462},
    "creatinine": {"gm/L": 0.01, "gm/dL": 0.001, "mg%": 1, "mg/dL": 1, "mg/mL": 0.01},
    "output": {"mL/min": 1, "L/hr": 0.06}
};

// get the inputs specific to this calculator (irl, this would come from the form fields)
var inputs = {
    "sex": {"value": "male"},
    "age": {"value": 30, "unit": "yr"},
    "weight": {"value": 150, "unit": "lb"},
    "creatinine": {"value": 0.008, "unit": "gm/L"}
};

// standardize all the inputs in the units of our equation
var standardized = {};
for (var key in inputs) {
    if ("unit" in inputs[key] || !inputs[key]["unit"]) {
        standardized[key] = inputs[key]["value"] / units[key][inputs[key]["unit"]];
    } else{
        standardized[key] = inputs[key]["value"];  // ignore those unit less inputs
    }
}

standardized["output"] = (standardized["sex"] == "male" ? 1.0 : 0.85) * (140 - standardized["age"]) * standardized["weight"] / (72 * standardized["creatinine"]);
output = standardized["output"] * units["output"]["mL/min"];  // desired output unit