Detailed explanation of the steps for jquery to operate json and define json

This time I will bring you a detailed explanation of the steps for jquery to operate json and define json. What are the precautions for jquery to operate json and define json? The following is a practical case, let's take a look.

1. Background

json is a lightweight data exchange format that is very conducive to the interaction between Java services and js. This article will introduce The simple definition of json and how js parses json.

2. Content

1. json definition:

The simple json format is [{"key1":"value1"},{"key2":"value2"}],

[] represents the array, {} represents the data in the array

Object, key1, key2 are the keys in a json object. The key value in a json is unique. value1, value2 are the values ​​corresponding to the key keys.

Definition method:

1) Directly spell the json string, for example: String variable , the content is [{"attchName":"Attachment 0","attchId":0},{"attchName":"Attachment 1","attchId":1},{"attchName":"Attachment 2","attchId ":2}].

2) Introduce the json-lib.jar open source jar package and define the JSONObject object, example:

JSONArray jsonArray = newJSONArray();JSONObject attchJson = newJSONObject();attchJson.put("attchId","0");
attchJson.put("attchName", "附件0");jsonArray.put(attchJson);jsonArray即为一个json数据，等价于用[]的定义一个json.

For complex json definition, the value corresponding to the key in json can also be a json array. For example, a task information is encapsulated in json. There are several attachments in this task. The definition method is as follows:

JSONArray taskJsonArray = newJSONArray();JSONObject taskJsonObj = newJSONObject();taskJsonObj.put("taskId",100);
taskJsonObj.put("taskName", "myTask");taskJsonObj.put("attchs",jsonArray);taskJsonArray.put(jsonObj);

taskJsonArray is the final one you want to get. json content, the form of

after simple string assembly is as follows:

[{"attchs":[{"attchName":"附件0","attchId":0},{"attchName":"附件1","attchId":1},{"attchName":"附件2","attchId":2}],"taskId":100,"taskName":"myTask"}]

2. JS parsing json##general of json Parsing method:

var json = eval_r(jsonArray );
 for(var i=0;i<json.length;i++){ 
 alert("attchId:"+json[i].attchId+",attchName:"+json[i].attchName);
}

Use jQuery to parse json:

 $.getJSON("jsonTest",{showNumber:"3"},function(data){    
 $.each(data,function(idx,item){
   //alert(idx);
   if(idx<0){
    returntrue;//同countinue，返回false同break
   } 
   alert("attchId:"+item.attchId+",taskName:"+item.attchName); 
   }); });

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

Recommended reading:

How to use JSON as a function parameter

Detailed explanation of how to handle WebService cross-domain issues

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