HTML interview questions(71-80)

How do I keep people from stealing my source code and/or images?

Because copies of your HTML files and images are stored in cache, it is impossible to prevent someone from being able to save them onto their hard drive. If you are concerned about your images, you may wish to embed a watermark with your information into the image. Consult your image editing program’s help file for more details.

The colors on my page look different when viewed on a Mac and a PC.

The Mac and the PC use slightly different color palettes. There is a 216 “browser safe” color palette that both platforms support; the Microsoft color picker page has some good information and links to other resources about this. In addition, the two platforms use different gamma (brightness) values, so a graphic that looks fine on the Mac may look too dark on the PC. The only way to address this problem is to tweak the brightness of your image so that it looks acceptable on both platforms.

How do you create tabs or indents in Web pages?

There was a tag proposed for HTML 3.0, but it was never adopted by any major browser and the draft specification has now expired. You can simulate a tab or indent in various ways, including using a transparent GIF, but none are quite as satisfactory or widely supported as an official tag would be.

My page looks good on one browser, but not on another.

There are slight differences between browsers, such as Netscape Navigator and Microsoft Internet Explorer, in areas such as page margins. The only real answer is to use standard HTML tags whenever possible, and view your pages in multiple browsers to see how they look.

How do I make sure my framed documents are displayed inside their frameset?

When the sub-documents of a frameset state are accessed directly, they appear without the context of the surrounding frameset.
If the reader’s browser has JavaScript support enabled, the following script will restore the frameset:

<SCRIPT TYPE="text/javascript">
if (parent.location.href == self.location.href) {
if (window.location.href.replace)
// causes problems with back button, but works
window.location.href = 'frameset.html';
A more universal approach is a "restore frames" link:
<A HREF="frameset.html" TARGET="_top">Restore Frames

Note that in either case, you must have a separate frameset document for every content document. If you link to the default frameset document, then your reader will get the default content document, rather than the content document he/she was trying to access. These frameset documents should be generated automatically, to avoid the tedium and inaccuracy of creating them by hand.
Note that you can work around the problem with bookmarking frameset states by linking to these separate frameset documents using TARGET=”_top”, rather than linking to the individual content documents.
How do I update two frames at once?

There are two basic techniques for updating multiple frames with a single link: The HTML-based technique links to a new frameset document that specifies the new combination of frames. The JavaScript-based solution uses the onClick attribute of the link to update the additional frame (or frames).

The HTML-based technique can link to a new frameset document with the TARGET=”_top” attribute (replacing the entire frameset). However, there is an alternative if the frames to be updated are part of a nested frameset. In the initial frameset document, use a secondary frameset document to define the nested frameset. For example:

<frameset cols="*,3*">
<frame src="contents.html" name="Contents">
<frame src="frameset2.html" name="Display">
<!-- Alternative non-framed version -->

A link can now use the TARGET=”Display” attribute to replace simultaneously all the frames defined by the frameset2.html document.
The JavaScript-based solution uses the onClick attribute of the link to perform the secondary update. For example:

<a href="URL1" target="Frame1" onClick="top.Frame2.location='URL2';">Update frames

The link will update Frame1 with URL1 normally. If the reader’s browser supports JavaScript (and has it enabled), then Frame2 will also be updated (with URL2).

Can I have two or more Submit buttons in the same form?

Yes. This is part of HTML 2.0 Forms support (some early browsers did not support it, but browser coverage is now excellent).
The submit buttons must have a NAME attribute. The optional VALUE attribute can be used to specify different text for the different submit buttons.
To determine which submit button was used, you need to use different values for the NAME and/or VALUE attributes. Browsers will send to the server the name=value pair of the submit button that was used. Here is an example:

<input type="submit" name="join" value="I want to join now">
<input type="submit" name="info" value="Please send full details">

Note that if you are using image submit buttons, you need to provide different NAME attributes for them too. Also, browser behavior can be inconsistent when the form is submitted without a submit button (e.g., by hitting ENTER).
If you’re unsure what results you’re going to get when you submit your form, TipJar has a standard script which you can use. Code this, for example (assuming method “post”):

<form method="post" action="">

and then go through the motions of submitting your form. The TipJar server decodes the form input, and displays the result to you.
How do I make a link or form in one frame update another frame?

In the frameset document (the HTML document containing the

<frameset> <frame> tags)

make sure to name the individual frames using the NAME attribute. The following example creates a top frame named “navigation” and a bottom frame named “content”:

<frameset rows="*,3*">
<frame name="navigation" src="navigation.html">
<frame name="content" src="content.html">
<!-- Alternative non-framed version -->

Then, in the document with the link, use the TARGET attribute to specify which frame should be used to display the link. (The value of the TARGET attribute should match the value of the target frame’s NAME attribute.) For example:

<a target="content" href=...>

To target a form submission, use the TARGET attribute of the FORM element, like this:

<form target="content" action=...>

Note that when forms are processed entirely by JavaScript, the target frame must be specified in the JavaScript. The value of the TARGET attribute is irrelevant.
Normally, the default target frame is the current frame (“_self”). To change the default target for every link/form on the page, use the TARGET attribute of the BASE element, like this:

<base target="content">

When I try to upload my site, all my images are X’s. How do I get them to load correctly?

They are a few reasons that this could happen. The most common are:

1. You’re attempting to use a .bmp or .tif or other non-supported file format. You can only use .gif and .jpg on the web. You must convert files that are not .gif or .jpg into a .gif or .jpg with your image/graphics program.
2. You’ve forgotten to upload the graphic files. Double-Check.
3. You’ve incorrectly linked to the images. When you are starting out, try just using the file name in

 <img> tag. If you have cat.jpg, use
img src="cat.jpg">.

4. Image file names are case-sensitive. If your file is called CaT.JpG, you cannot type cat.jpg, you must type CaT.JpG exactly in the src.
5. If all of the above fail, re-upload the image in BINARY mode. You may have accidentally uploaded the image in ASCII mode.

Is there a site that shows which tags work on which browsers?

There have been several attempts to do this, but I’m not aware of any really good source of comparisons between the browsers. The trouble is that there are many different versions of each browser, and many different tags. All current browsers should support the tags in the official HTML 3.2 specification, but the major ones also support nonstandard tags and sometimes have slightly different implementations. One place that has fairly good compatibility info is Browsercaps.

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