XML DOM firstChild Atributo

Element 对象

Definisyon at paggamit

firstChild This property returns the first child node of the selected element

If the selected node has no child nodes, this property returns NULL.

Syntax

elementNode.firstChild
Tips and Notes

Note:Firefox and most other browsers treat whitespace or newlines as text nodes, while Internet Explorer does not. Therefore, in the following example, we use a function to check the node type of the first child node.

Element nodes have a nodeType of 1, so if the first child node is not an element node, it will move to the next node and check if that node is an element node. This will continue until the first child node (which must be an element node) is found. This ensures that the result is correct in all browsers.

Tip:For more information on differences between browsers, please visit the DOM Browsers section in the XML DOM tutorial.

Example

The following code loads "books.xml" into xmlDoc and gets the first child node:

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
   if (this.readyState == 4 && this.status == 200) {
       myFunction(this);
   }
};
xhttp.open("GET", "books.xml", true);
xhttp.send();
// Check if the first node is an element node
function get_firstchild(n) {
    var x = n.firstChild;
    while (x.nodeType != 1) {
        x = x.nextSibling;
    }
    return x;
}
function myFunction(xml) {
    var x, i, txt, firstNode, xmlDoc;
    xmlDoc = xml.responseXML;
    x = xmlDoc.documentElement;
    txt = "";
    firstNode = get_firstchild(x);
    for (i = 0; i < firstNode.childNodes.length; i++) {
        if (firstNode.childNodes[i].nodeType == 1) {
            // Process only element nodes
            txt += firstNode.childNodes[i].nodeName +""
            " = " +
            firstNode.childNodes[i].childNodes[0].nodeValue + "<br>";
        }
    }
    document.getElementById("demo").innerHTML = txt;
}

亲自试一试

Element 对象