1) document.write() is used to insert or write codes in JavaScript.
2) window.prompt() opens up with a dialog box which asks the user to input some data and is there till the user cancels or submits the data.
3) window.alert() displays information in a pop-up dialog box on the screen to alert the user.
4) window.confirm() opens a dialog box with a message seeking for confirmation of the user.
5) parselnt() converts string to integer.
6) parseFloat() converts string to floating point number.
