msgbox example

message boxes

Message boxes are used to alert, prompt for input or confirm action from the user.
Examples: Click the gray buttons below to pop the message boxes
To alert the user of something (trivial or not):

The alert box has no consequences. Programmers often use them to test their script flows.
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To prompt the user for an input:

The input would then be used in the script for some purpose.
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To confirm with the user on an action:

The script will then respond to the user's action (OK[true] or Cancel[false])
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javascript - basic stuffs