eValid™ -- Automated Web Quality Solution Browser-Based, Client-Side, Functional Testing & Validation, Load & Performance Tuning, Page Timing, Website Analysis, and Rich Internet Application Monitoring.

Introduction
This page describes certain aspects of eValid's processing of web pages that contain errors.

Background: eValid vs. IE
eValid is build using the IE DLLs to ensure that it renders pages identically with the IE browser. However, even though eValid uses the same DLLs as IE, the topmost structure of eValid does NOT replicate all of IE's features.

We have learned from Microsoft IE actually incorporates a number of "failure tolerant" features that are not included in eValid. Examples of these errors include (but are not limited to):

• Malformed HTML (HTML passages that cannot be recovered sensibly).
• Malformed JavaScript.
• JavaScript passages that involve loops and other kinds of runtime errors.

By design, eValid is intended to be a quality control engine, so in our view it is inappropriate to mask user errors the way IE does.

Diagnostic Process
While IE does not have a JavaScript debugging feature (which is optional) eValid does not have this facility.

However, the FireFox does have a facility that can be used diagnostically. In the FireFox browser if you select to view the FireFox JavaScript console you will be able to see all JavaScript errors that arise at the FireFox JavaScript engine interprets the submitted JavaScrip. While this is not 100% certain, it is highly likely that errors in JavaScript that are suppressed by the IE error tolerance capability will show up here.

eValid Response to JavaScript Errors
eValid shows JavaScript errors that it encounters by changing the icon in the lower left corner of the eValid browser face.

Here is the normal lower left corner icon (normal operation): , and here is the changed icon (JavaScript error state): .

When you seen this latter icon you know that some kind of JavaScript error was encountered. Please note that eValid does NOT have facilities in the current versions to assist in analyzing or debugging these errors.

Notes from Web Search About IE Error Tolerance
A number of references we found in web searches about IE error tolerance and related subjects include these nuggets:

• One user reported on SlashDot that he found that IE consistently handles "malformed" input very well. It seems that IE is "...quite well known for its tolerance to almost everything you can throw at it."

• Michael Zalewski wrote a short program that throws HTML with seeded flaws at various browsers, and all but IE failed fairly consistently. He says that IE tolerated null pointer references, memory corruption, bugger overflows, memory exhaustion, and even was able to get past parsing illegal tags.

• We have had several customers complain that "eValid is broken" when in fact the page that eValid is presented has any number of very ugly problems, including infinite loops.