javascript 权威指南 学习笔记3：javascript 作用域
this keyword refers to the object on which the event occurred.
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<script>// This function recursively looks at Node n and its descendants, // replacing all Text nodes with their uppercase equivalents.function uppercase(n) { if (n.nodeType == 3 /*Node.TEXT_NODE*/) { // If the node is a Text node, create a new Text node that // holds the uppercase version of the node's text, and use the // replaceChild( ) method of the parent node to replace the // original node with the new uppercase node. var newNode = document.createTextNode(n.data.toUpperCase( )); var parent = n.parentNode; parent.replaceChild(newNode, n); } else { // If the node is not a Text node, loop through its children // and recursively call this function on each child. var kids = n.childNodes; for(var i = 0; i < kids.length; i++) uppercase(kids[i]); }}</script><!-- Here is some sample text. Note that the <p> tags have id attributes. --><p id="p1">This <i>is</i> paragraph 1.</p><p id="p2">This <i>is</i> paragraph 2.</p><!-- Here is a button that invokes the uppercase( ) function defined above. --><!-- Note the call to document.getElementById( ) to find the desired node. --><button onclick="uppercase(document.getElementById('p1'));">Click Me</button>
