Javascript Function!!

[Frank100]

Hi Guys...I do not have very good knowledge in Javascript...So please help me out to write a right function...

protected void txtEstimatedContractTotal_TextChanged(object sender, EventArgs e)
        {
            
            if (m_bChangeOccuring)
                return;
            m_bChangeOccuring = true;
            double dPercent = 0;
            try
            {
                dPercent = Convert.ToDouble(txtPercentage.Text);
                txtEstimatedCommission.Text = Convert.ToString(Convert.ToDouble(txtEstimatedContractTotal.Text) * dPercent);
                txtBalance.Text = Convert.ToString(Convert.ToDouble(txtFinalContractTotal.Text) - Convert.ToDouble(txtDepositReceived.Text) - Convert.ToDouble(txtBalanceReceived.Text));
            }
            catch (Exception ex)
            {
            }
            m_bChangeOccuring = false;
        }

This is the function which I have written in C# in .cs file...I wanna write the same function in Javascript....so please help me to write this function in Javascript..