In this example, you can click the first button as many times as you want.
In practice this can cause a form to be submitted, or some other event triggered, more than once.
For details, see the Script and Style elements section of the XHTML 1.0 Recommendation as well as the HTML compatibility guideline for embedded scripts.
Another common error occurs when including a This example generates an error for "unknown entity section" because the "&" is assumed to begin an entity reference.
Authors should avoid using strings such as "" in their embedded scripts.
In Java Script, authors may use a backslash to prevent the string from being parsed as markup: , authors must also take care when using start tags within a script element.
To test, click the Submit button twice in quick succession.If you don't want this, read on for some work-arounds.Rather than simply disabling the button, we can also change the text so that people don't get confused.To avoid problems with both validators and browsers, always use & in place of & when writing If you receive the error "Missing a required sub-element of HEAD", check that you have included the TITLE element in the HEAD.The TITLE element is required in all HTML documents.