Summary of JSON and XML knowledge points

This article mainly shares with you a summary of js knowledge points.JSON objects are written in curly brackets ({}). An object can contain multiple key/value pairs. The key must be a string, and the value can be a legal JSON data type (string, number, object, array, boolean or null).
Use colon (:) to separate key and value.
Each key/value pair is separated by commas (,).

**eg:**var myjson={“name”:”zhangsan”, “age”:15};
Two ways to access object values:

1. myjson.name

2. myjson["name"]

for..in can be accessed iteratively Object

for(x in myjson) {
x is the name of the key in the object. When accessing the value here, you can only use the second method above
myjson[x]
}

Use delete to delete the attributes of the json object

delete myjson.name
delete myjson[“name”]

The difference between json object, json string and json array

var str2 = { “name”: “asan”, “sex” : "man" };//Object
var str1 = ‘{ “name”: “deyuyi”, “sex”: “man” }’;//String
var sites = [
{ “name”:”runoob” , “url”:”www.runoob.com” },
{ “name”:”google” , “url”:”www.google.com” },
{ “name”:”微博” , “url”:”www.weibo.com” }
];//Array
Array access: sites[0].name; return runoob

JSON.parse()

Convert the string into a JavaScript object.
JSON cannot store Date objects and needs to be converted into strings for storage
For details, please visit the URL

JSON.stringify()

Convert JavaScript objects into strings.
JSON cannot store Date objects.
JSON.stringify() will convert all dates to strings.
For details, please visit the website

XML

XML tutorial for rookies

Parsing XML strings

txt =”“;
txt=txt+”Everyday Italian”;
txt=txt+”Giada De Laurentiis”;
txt=txt+”2005”;
txt=txt+””;
if (window.DOMParser)
{
parser=new DOMParser();
xmlDoc=parser.parseFromString(txt,”text/xml”);
}
else // Internet Explorer
{
xmlDoc=new ActiveXObject(“Microsoft.XMLDOM”);
xmlDoc.async=false;
xmlDoc.loadXML(txt);
}
Internet Explorer uses the loadXML() method to parse XML strings, while other browsers use the DOMParser object.

Parse XML document

if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject(“Microsoft.XMLHTTP”);
}
xmlhttp.open(“GET”,”books.xml”,false);
xmlhttp.send();
xmlDoc=xmlhttp.responseXML;

The syntax for extracting text from an element is:

xmlDoc. getElementsByTagName(“to”)[0].childNodes[0].nodeValue;

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