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| docs:programming:javascript:javascript_notes [2007/03/13 16:39] – created billh | docs:programming:javascript:javascript_notes [2008/08/03 00:25] (current) – external edit 127.0.0.1 | ||
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| ====== JavaScript Notes ====== | ====== JavaScript Notes ====== | ||
| - | ===== Base Template | + | ===== Baseline Example |
| <code html> | <code html> | ||
| < | < | ||
| Line 26: | Line 26: | ||
| </ | </ | ||
| </ | </ | ||
| + | </ | ||
| + | |||
| + | ===== Getting a reference for an element in any browser===== | ||
| + | * The standard way is document.getElementById(" | ||
| + | * IE uses document.all(" | ||
| + | * Older Netscape browsers used document.layers[elemID] | ||
| + | * A utility function to get the proper element reference, regardless of browser:< | ||
| + | function getElem(elemID){ | ||
| + | if(document.all){ | ||
| + | return document.all(elemID); | ||
| + | }else if(document.getElementById){ | ||
| + | return document.getElementById(elemID); | ||
| + | }else if(document.layers){ | ||
| + | return document.layers[elemID]; | ||
| + | } | ||
| + | } | ||
| + | |||
| + | ...before doing anything with the object, you can make sure you have a valid object like this: | ||
| + | var elem = getElem(" | ||
| + | if(elem){ | ||
| + | // elem is valid, so proceed with code | ||
| + | } | ||
| + | </ | ||
| + | |||
| + | ===== Commenting ===== | ||
| + | <code javascript> | ||
| + | <SCRIPT language=" | ||
| + | |||
| + | <!-- This opens the HTML comments that will hide the script from old browsers | ||
| + | |||
| + | // javascript comment | ||
| + | ......Javascript Statements....... | ||
| + | |||
| + | /* | ||
| + | multi-line | ||
| + | javascript | ||
| + | comment | ||
| + | */ | ||
| + | |||
| + | //--> This closes the comment section and the browser will read on normally | ||
| + | |||
| + | </ | ||
| + | </ | ||
| + | |||
| + | ===== Linking to an external script file ===== | ||
| + | <code javascript> | ||
| + | // in the < | ||
| + | <script type=" | ||
| + | </ | ||
| + | |||
| + | ===== Testing for existence of a property or method ===== | ||
| + | <code javascript> | ||
| + | if(elem && typeof elem.property != " | ||
| + | // element property is valid - it is safe to use this property | ||
| + | } | ||
| + | |||
| + | if(elem && typeof elem.method != " | ||
| + | // element method is valid - it is safe to call this method | ||
| + | } | ||
| </ | </ | ||