1- It should only allow numbers (negative as well) and "." To be entered.
2- It should format the number as 1,234,567,789.123456789. It should execute such that the the commas are put while typing.
3- It should also only allow numbers that are as big as double can handle.
Using the code
On the textbox on which the formatting needs to be applied, use the following code
onkeypress="return ValidateNumberKeyPress(this, event);" onkeyup="ValidateNumberKeyUp(this);"
Points of Interest
Script is preety easy to read and understand. Some references that were used during the course of the script creation