json overview

1. Concept

Concept: JavaScript Object Nation, js object notation

Function: Mainly realize the storage and exchange of information

Features: fast speed, small footprint, easy to analyze

Syntax: The data in json consists of key-value pairs.

Key: Enclosed by double quotes or single quotes.

Value: numeric value (decimal, integer), string, boolean (false, true)

eg：

{
    
     "name" : "zs"，"age" : 20，"gender" : false }

Array: Array [element 1, element 2...]

{
    
     "users" : [
    {
    
     "name" : "zs"，"age" : 20，"gender" : false },
    {
    
     "name" : "ls"，"age" : 21，"gender" : true },
    {
    
     "name" : "ww"，"age" : 20，"gender" : true },
    ...
]}

json object:

1. The data content consists of key-value pairs, which are connected by colons, and the key-value pairs and key-value pairs are separated by commas
2. Use square brackets for arrays
3. json object uses braces

Obtaining json data:

1. json object.key
2. json object["key"]
3. Array object [index]

The way to traverse the json object:

for(var t in user){
    
    
alert(user[t]);
}

1. t is each key in the user object currently to be traversed
2. The obtained t is in the form of a string, so the value needs to be obtained through user[t]
3. If you use this loop to traverse the array in the json object, then t is the index