o_19octlt3v29m1ul81r9513q81i4ra.pdf

JavaScript, Briefly 291
The example shown in the preceding exercise placed the tags and the JavaScript
code within the tag. You can also place tags and related code within
the block.
JavaScript includes methods for choosing or selecting elements on a page. For example,
the JavaScript method getElementById() selects an element on a Web page based on its
id attribute. JavaScript includes other similar methods as well, such as getElementsbyTag
Name() which returns all the elements of a certain tag type, such as all the elements
on a page.
In the following exercise, you will retrieve the element that has an id attribute of
contentDiv (as you saw in the previous exercise) and change its background color to
a shade of gray.
SET UP Use the Javascript01.html file that you created in the previous exercise. Open
the file in Notepad, if it is not already open.
1. Delete the following line from the code:
alert("hello world");
2. Between the and tags, place the following:
var divContent = document.getElementById("contentDiv");
divContent.style.backgroundColor = "#abacab";
3. Save your work in Notepad.
4. Open the file in Internet Explorer to test it. Instead of a Hello World dialog box, the
text on the page appears with a gray background:
CLEAN UP Close Internet Explorer. Leave the Javascript01.html file open in Notepad
for the next exercise.
In this example, the code retrieves the element identified in the page with the id of
contentDiv by using the getElementById method. It places that element into a variable
called divContent and uses that variable with another JavaScript function, style(), to
change the div element’s backgroundColor property value to #abacab.