Definition: The confirm function that is predefined for use in Javascript is similar to the alert function in that it will display a popup message on the screen. The difference with confirm is that as well as the OK button there is also a Cancel button. One of these needs to be selected to make the message disappear. The confirm function will return true if the OK button is selected and false if the Cancel button is selected allowing different actions to be taken depending on which button is selected.

This is not a reserved word so you can declare your own variable or function called confirm but if you do then you will not be able to use the built-in function.

Examples: if (confirm('Ready to Send?')) sendData();