前端学习5（html dom）(JSON)
程序员文章站
2024-03-20 10:20:40
...
找寻方法
| document.getElementById(id) | |
| document.getElementsByTagName(name) |
var x = document.getElementsByTagName("p"); document.getElementById("demo").innerHTML = 'The first paragraph (index 0) is: ' +x[2].innerHTML; |
| document.getElementsByClassName(name) |
处理方法
document.write();
document.getElementById(id).innerHTML="hello";
document.getElementById("myImage").src ="landscape.jpg"; //change attribute
document.getElementById("p2").style.color ="blue"; //change css
<h1 onclick="this.innerHTML = 'Ooops!'">Click on this text!</h1>
对节点的定义
- parentNode
- childNodes[nodenumber]
- firstChild
- lastChild
- nextSibling
- previousSibling
节点属性
document.getElementById("id01").nodeName
document.getElementById("id01").nodeType
document.getElementsByTagName("p").length
| ELEMENT_NODE | 1 | <h1 class="heading">W3Schools</h1> |
| ATTRIBUTE_NODE | 2 | class = "heading" (deprecated) |
| TEXT_NODE | 3 | W3Schools |
| COMMENT_NODE | 8 | <!-- This is a comment --> |
| DOCUMENT_NODE | 9 | The HTML document itself (the parent of <html>) |
| DOCUMENT_TYPE_NODE | 10 | <!Doctype html> |
<script>
var para = document.createElement("p");
var node = document.createTextNode("This is new.");
para.appendChild(node); //append the text node to the <p> element:
var element = document.getElementById("div1");
element.appendChild(para);
</script>JavaScript Object Notation(for stroage and exchange data) json就是一个text，也可以理解为string
JSON uses JavaScript syntax, but the JSON format is text only.
Text can be read and used as a data format by any programming language.
成对出现，“”括起，{}括起object []array
与xml区别：
XML has to be parsed with an XML parser. JSON can be parsed by a standard JavaScript function. （更快read write，short）
可以在object中套用object（myObj.cars["car2"] // myObj.cars.car2）如果cars是array 用myObj.cars[2]
myObj = {"name":"John","age":30, "car":null };
x = myObj.name;
x = myObj.name;
x = myObj["name"];
for (xin myObj) {
document.getElementById("demo").innerHTML+= x; //输出 name,age car
document.getElementById("demo").innerHTML+= x; //输出 name,age car
document.getElementById("demo").innerHTML+= myObj[x]; //输出 john 30 null
}
JSON.parse() to convert text into a JavaScript object:
var arr = ["John", "Peter","Sally", "Jane" ];
var myJSON = JSON.stringify(arr); //将js转化为json
var myJSON = JSON.stringify(arr); //将js转化为json
request JSON from the server by using an AJAX request //利用XMLHttpRequest
下一篇： 最长公共子序列问题