json format, object navigation

json has two formats:

1) Object format: {"key1":obj,"key2":obj,"key3":obj...}

2) Array /collection format: [obj,obj,obj...]

 

For example: user object is represented in json data format

{"username":"zhangsan","age":28,"password":"123","addr":"北京"}

 

<script language="JavaScript">

　　var person = {"firstname":"张","lastname":"三丰","age":100};

　　//取出lastname
　　alert(person.lastname);
　　//取出age
　　alert(person.age);

</script>

 

List<Product> is represented in json data format

[{"pid":"10","pname":"小米4C"},{},{}]

 

<script language="JavaScript">
　　* 案例二
　　* [{key:value,key:value},{key:value,key:value}]

　　var persons = [
　　{"firstname":"张","lastname":"三丰","age":100},
　　{"firstname":"李","lastname":"四","age":25}
　　];

　　//取出 firstname=李
　　alert(persons[1].firstname);
　　//取100
　　alert(persons[0].age);
</script>

 

Note: Object format and array format can be nested within each other

<script language="JavaScript">
* 案例三
* {
* "param":[{key:value,key:value},{key:value,key:value}]
* }

var json = {
　　"baobao":[
　　　　{"name":"小双","age":28,"addr":"扬州"},
　　　　{"name":"建宁","age":18,"addr":"紫禁城"},
　　　　{"name":"阿珂","age":10,"addr":"山西"},
　　]
};

//取name = 建宁
alert(json.baobao[1].name);

//取addr 山西
alert(json.baobao[2].addr);

</script>

Note: The key of json is a string and the value of jaon is Object

 

Parsing of json:

JSON is the native content of js, which means that js can directly retrieve the data in the json object