We use XHTML+CSS to redesign our website. How do we know that the pages we create really comply with web standards? W3C and some volunteer websites provide online verification programs to help us check whether the pages comply with standards and provide corrections. Wrong help message. These checks are very useful and are the first thing I do when debugging a page.
1.XHTML validation
Verification URL: http://validator.w3.org/
Verification method: URL verification, file upload verification
If the verification is successful, "This Page Is Valid XHTML 1.0 Transitional!" will be displayed.
If the verification fails, more verification options and error messages will be displayed.
Generally, selecting "Show Source" and "Verbose Output" can help you find the line where the error code is located and the cause of the error.
Comparison table of common XHTML validation error causes
No DOCTYPE Found! Falling Back to HTML 4.01 Transitional--DOCTYPE is not defined.
No Character Encoding Found! Falling back to UTF-8.--Undefined language encoding.
end tag for "img" omitted, but OMITTAG NO was specified--The image tag is not closed with "/".
an attribute value specification must be an attribute value literal unless SHORTTAG YES is specified--The attribute value must be quoted.
element "DIV" undefined---DIV tags cannot be in uppercase and must be changed to lowercase div.
required attribute "alt" not specified---The image needs to add the alt attribute.
required attribute "type" not specified---The tag called by JS or CSS misses the type attribute.
One of the most common errors is the capitalization of labels. Often these errors are related, such as forgetting an other
2.CSS2 validation
Verification URL: http://jigsaw.w3.org/css-validator/
Verification method: URL verification, file upload verification, direct code verification
If the verification is successful, "Congratulations, this document has passed the style sheet verification!" will be displayed.
If the verification fails, two types of errors will be displayed: errors and warnings. The error means that it must be corrected, otherwise it will not pass the verification; the warning means that there is code that is not recommended by W3C and it is recommended to modify it.
Comparison table of common CSS2 validation error causes
(Error) Invalid number: color909090 is not a color value: 909090 ---The hexadecimal color value must be added with a "#" sign, that is, #909090
(Error) Invalid number: margin-topUnknown dimension: 6pixels ---pixels is not a unit value, the correct way to write it is 6px
(Error) The property scrollbar-face-color does not exist: #eeeeee --- Defining the scrollbar color is a non-standard property
(Error) The value cursorhand does not exist: hand is a non-standard attribute value, modified to cursor:pointer
(Warning) Line: 0 font-family: It is recommended that you specify a type family as the last choice--W3C recommends that when defining fonts, end with a type of font, such as "sans-serif", to ensure that it can be used in different operations Under the system, web fonts can be displayed.
(Warning) Line: 0 can't find the warning message for otherprofile --Indicates that there are non-standard attributes or values in the code, and the verification program cannot determine and provide corresponding warning information.
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