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HTML cơ bản - p 11

84 Chapter 2: The HTML Language Example 2.21: A table with spanned rows and columns (continued) Venus 108,200,000.72225 days243 days Earth 149,600,0001.0365 days24 hrs Mars 227,900,0001.5687 days24.6 hrs Figure 2.21 shows how the code in Example 2.21 appears in a browser. Figure 2.21: A table with spanned rows and columns number of cells in a row or column. This generally yields unpredictable results. Initially a web designer’s best friend, tables have fallen out of favor recently because robots and editing software have difficulty understanding them due to their complexity. When tables are coded by hand, the author. | 84 Chapter 2 The HTML Language Example 2.21 A table with spanned rows and columns continued th Venus th td 108 200 000 td td .72 td td 225 days td td 243 days td tr tr th Earth th td 149 600 000 td td 1.0 td td 365 days td td 24 hrs td tr tr th Mars th td 227 900 000 td td 1.5 td td 687 days td td 24.6 hrs td tr table body html Figure 2.21 shows how the code in Example 2.21 appears in a browser. AHA Exampl 7 71 Distance from sun Year Length Day Length Kilometers AUs Mercury 57 900 POO 38 88 days 59 days Venus 108200.000 .72 225 days 243 days Earth 149 600 000 1.0 365 days 24 hrs Mars 227 900.000 13 687 days 24.6 hrs The Inner Planets Figure 2.21 A table with spanned rows and columns It goes without saying that web developers must be careful when using the rowspan and colspan attributes not to wind up with a table that has the wrong number of cells in a row or column. This generally yields unpredictable results. Initially a web designer s best friend tables have fallen out of favor recently because robots and editing software have difficulty understanding them due to their complexity. When tables are coded by hand the author generally knows From the Library of Wow eBook Links and Anchors 85 what kind of content will go into the cells. However when tables are generated by server-side scripts drawing content from a database it is less certain what content if any will go into a given row or cell. Therefore extra care is needed to deal with null data values and edge conditions. Links and Anchors Links are the lifeblood of the Web and Hypertext is the name of the Markup Language. That said link is a strange word. It is both a noun and a verb and its use is loose. And how can a link be hyper Two elements in HTML the anchor and area elements when used with an href hypertext reference attribute create hyperlinks. A third element the link element link can also create hyperlinks when used with certain attributes. It is a document head element providing a means for web authors