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What is HTML DOM? Application explanation of HTML DOM

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Release: 2018-10-13 17:06:06
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The content of this article is about what is HTML DOM? The explanation of the application of HTML DOM has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

What is DOM?

DOM (Document Object Model) is translated as Document Object Model and is a programming interface for HTML and XML documents.
HTML DOM defines standard methods for accessing and manipulating HTML documents.
DOM expresses HTML documents in a tree structure.

What is HTML DOM? Application explanation of HTML DOM

HTML DOM defines the objects and properties of all HTML elements, as well as the methods to access them.

In other words, HTML DOM is a standard on how to get, modify, add or delete HTML elements.

According to the HTML DOM standard, all content in HTML is a node.

The entire document is a document node
Each HTML element is an element node
The text within an HTML element is a text node
Each HTML attribute is an attribute node
Comments are comment nodes

Some methods of HTML DOM

getElementById(id) - 获取带有指定 id 的节点(元素)
appendChild(node) - 插入新的子节点(元素)
removeChild(node) - 删除子节点(元素)
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Some attributes of HTML DOM

innerHTML - 节点(元素)的文本值
parentNode - 节点(元素)的父节点
childNodes - 节点(元素)的子节点
attributes - 节点(元素)的属性节点
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Application: Dynamically add a city

Requirement: When we visit a web page, add an address that is not on the web page

nbsp;html>


    <meta>
    <title>动态添加城市</title>
    <script>
        function add_city() {
        // 1. 获取输入框值
        var cityEle= document.getElementById(&#39;city&#39;).value;
        // 2. 创建城市的文本节点
        var citynode = document.createTextNode(cityEle);
        // 3. 创建li的元素节点
        var linode = document.createElement("li");
        // 4. 把城市的文本节点,添加到li元素节点中
        linode.appendChild(citynode);
        // 5. 获取顺序列表ol标签的值
        var ulEle = document.getElementById(&#39;city_line&#39;);
        // 6. 将li元素节点添加到ol标签里
        ulEle.appendChild(linode);
        }
    </script>


    <input>
    // 确定事件类型'onclick'
    <input>

    <ol>
        <li>西安</li>
        <li>拉萨</li>
        <li>成都</li>
    </ol>

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What is HTML DOM? Application explanation of HTML DOM

What is HTML DOM? Application explanation of HTML DOM

##Application: City’s secondary linkage

The so-called secondary linkage is through a drop-down list The selection displays the corresponding data in another select drop-down list. For example, I have two drop-down lists. The first list is for selecting provinces. If I select a certain province, the other list will also display the cities in that province.

nbsp;html>


    <meta>
    <title>二级联动(城市)</title>
    <style>
        div{
            margin: 0 auto;
            text-align: center;
            margin-top: 100px;
        }
    </style>
    <script>
        function choice_city() {
            // 2.1 获取用户选择的省份
            var province_Ele  = document.getElementById(&#39;province&#39;).value;
            // 2.2 创建一个二维数组,用来存放省份和城市的对应关系
            var cities = new Array(3);
            cities[0] = new Array(&#39;西安&#39;,&#39;咸阳&#39;,&#39;宝鸡&#39;);
            cities[1] = new Array(&#39;成都&#39;,&#39;绵阳&#39;,&#39;遂宁&#39;);
            cities[2] = new Array(&#39;济南&#39;,&#39;青岛&#39;,&#39;临沂&#39;);
            // 3 获取用户选择的城市
            var seleceEle = document.getElementById(&#39;city&#39;);
            // 4 清空第二个下拉列表的内容
            seleceEle.options.length = 1 ;
            // 2.3 遍历二维数组,比较省份编号和用户选择的省份
            for(var i = 0;i<cities.length;i++){
                // 2.4 如果选择省份编号为i,遍历城市
                if (province_Ele == i){
                    for(var j = 0;j<cities[i].length;j++){
                        // 2.5 创建城市的文本节点
                        var citynode = document.createTextNode(cities[i][j]);
                        // 2.6 创建option的属性节点
                        var optionnode = document.createElement(&#39;option&#39;);
                        // 2.7 将城市文本添加到option属性节点
                        optionnode.appendChild(citynode);
                        // 2.8 将option内容添加到select元素里面
                        seleceEle.appendChild(optionnode)
                    }
                }
            }
        }
    </script>


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        籍贯         // 1. 确定事件类型onchange, 并为其绑定一个函数                       

What is HTML DOM? Application explanation of HTML DOM

What is HTML DOM? Application explanation of HTML DOM

##

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