The message html web page is a simple page containing a little JavaScript that allows a user to leave messages for him her self The messages are simply strings stored in a in the page When a new message is submitted to the page it is appended to the end of the existing messages, and the result is shown in the A copy of the messages is also stored in a hidden form field in the form that submits the new message to the page so that the existing messages will not be lost (unless the user leaves the page entirely) Use the page to leave a number of messages to yourself Then see if you can insert unexpected HTML elements into the page that might cause a user to do, or go, somewhere not intended by the developer of the page This is message html Get the query string (if any) var queryString window location search queryString decodeURIComponent(queryString) Figure out where the new message is in the query string var messageLoc queryString indexOf( ) var endMessage queryString indexOf( ,messageLoc 1) Extract the message from the string var message queryString substring(messageLoc 1,endMessage) Figure out where the previous messages are located in the query string var messagesLoc queryString indexOf( ,endMessage) Extract the previous messages var messages queryString substring(messagesLoc 1) Set the messages variable appropriately (is this the first message to be sent, or not ) if (messages length 0) messages decodeURIComponent(message) else messages decodeURIComponent(messages message) Message Board Message Insert text into message board div and hidden form field value so we don't lose them (Change the signs back into spaces a side effect of the URL encoding and decoding process ) document getElementById('messageboard') innerHTML decodeURIComponent(messages) replace( g, ) document getElementById('messages') value encodeURIComponent(messages)

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The message.html web page is a simple page containing a little JavaScript that allows a user to leave messages for him-/her-self. The messages are simply

The message.html web page is a simple page containing a little JavaScript that allows a user to leave messages for him-/her-self. The messages are simply strings stored in a

in the page. When a new message is submitted to the page it is appended to the end of the existing messages, and the result is shown in the

. A copy of the messages is also stored in a hidden form field in the form that submits the new message to the page so that the existing messages will not be lost (unless the user leaves the page entirely). Use the page to leave a number of messages to yourself. Then see if you can insert unexpected HTML elements into the page that might cause a user to do, or go, somewhere not intended by the developer of the page.

===This is message.html===