A short explanation of the options is listed below.
eval function by default.
Press Insert HTML to insert the input verbatim as HTML code. By default it is inserted into a
div in the page using the
Press Clear Output clear the output area. The output area is normally cleared between computations, but this behavior can be turned off.
Press Clear Insert clear the inserted HTML previously added with the Insert HTML button. This removes any type of inserted content, even closing an opened window.
The page retains a history of previously (sucessfully) evaluated expressions.
The < button backtracks to the previous input in the history, and displays the computed output. The output is not recomputed. The > button goes forward again. Any new expression evaluated truncates the history to the current position.
The result of the previous computation is stored in a global variable
The ^ and v buttons change the size of the input area.
The Examine depth setting determines how far to recurse when examining objects. The default lists the properties of the object, but not the properties of the properties. Rarely needs changing.
The Insert method setting determines how the Insert HTML button inserts the HTML code. There are three options:
innerHTMLproperty of an empty
div. This is the default.
iframeelement is inserted into the empty
divand the HTML is written to this frame using
window.open, and the HTML is written to this window using
The Autoclear checkbox determines whether the output area is cleared between computations. The default is on.
eval function (as a Program) or with the
Function constructor (as a Function Body). The default is to use
The Catch Errors checkbox determines wheter the evaluation is contained in a
catch block or whether the errors are left uncaught and handled by the browser. The default is catch errors.
When inserted content creates a new page (using the iframe or linked window insertion methods), evaluation is performed in the scope of these pages' window objects, i.e., the global objects of the inserted pages.
The apparent change of global object is emulated by wrapping the
with construct. The emulation
is not perfect, since new global variables are placed in the original
page's global object, but it is usually sufficient.
Examining values or DOM nodes works on the new page as well.