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How jquery reads json parameters

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Release： 2023-01-04 09:36:34

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How jquery reads json parameters: 1. Use jQuery to parse the Json data format, and set the parameter [dataType: "json"] in the Ajax request; 2. Use jQuery to parse the Json object, the code is [data = $.parseJSON string].

How jquery reads json parameters

The operating environment of this tutorial: windows7 system, jquery3.2.1 version, Dell G3 computer.

Recommended: jquery video tutorial

How to read json parameters with jquery:

1. jQuery parsing Json data format:

Using this method, you must set parameters in the Ajax request:

dataType: "json"

Get the data returned through the callback function and parse it to get the value we want. See the source code:

jQuery.ajax({ 
url: full_url, 
dataType: "json", 
success: function(results) { 
alert(result.name); 
} });

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Normally, you can return JSON data from the background and leave the frontend to jQuery.

jquery asynchronous request sets the type (usually this configuration attribute) to "json", or uses the $.getJSON() method to obtain the server return, then there is no need for eval () method, because the result obtained at this time is already a json object, you only need to call the object directly. Here is the $.getJSON method as an example

Example 1

The code is as follows:

var data=" 
{ 
root: 
[ 
{name:&#39;1&#39;,value:&#39;0&#39;}, 
{name:&#39;6101&#39;,value:&#39;北京市&#39;}, 
{name:&#39;6102&#39;,value:&#39;天津市&#39;}, 
{name:&#39;6103&#39;,value:&#39;上海市&#39;}, 
{name:&#39;6104&#39;,value:&#39;重庆市&#39;}, 
{name:&#39;6105&#39;,value:&#39;渭南市&#39;}, 
{name:&#39;6106&#39;,value:&#39;延安市&#39;}, 
{name:&#39;6107&#39;,value:&#39;汉中市&#39;}, 
{name:&#39;6108&#39;,value:&#39;榆林市&#39;}, 
{name:&#39;6109&#39;,value:&#39;安康市&#39;}, 
{name:&#39;6110&#39;,value:&#39;商洛市&#39;} 
] 
}";

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jquery

$.getJSON("https://www.jb51.net/",{param:"sanic"},function(data){ 
//此处返回的data已经是json对象 
//以下其他操作同第一种情况 
$.each(data.root,function(idx,item){ 
if(idx==0){ 
return true;//同countinue，返回false同break 
} 
alert("name:"+item.name+",value:"+item.value); 
}); 
});

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2. jQuery parses Json objects:

jQuery provides another Method "parseJSON", which takes a standard JSON string and returns the resulting JavaScript object. Let's take a look at the syntax:

The code is as follows:

data = $.parseJSON(string);

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See how it is applied to actual development:

jQuery.ajax({ 
url: dataURL, success: function(results) { 
var parsedJson = jQuery.parseJSON(results); 
alert(parsedJson.name); 
} 
});

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Supplementary:

Complete example of jquery parsing json data:

var data=" 
{ 
root: 
[ 
{name:&#39;1&#39;,value:&#39;0&#39;}, 
{name:&#39;6101&#39;,value:&#39;北京市&#39;}, 
{name:&#39;6102&#39;,value:&#39;天津市&#39;}, 
{name:&#39;6103&#39;,value:&#39;上海市&#39;}, 
{name:&#39;6104&#39;,value:&#39;重庆市&#39;}, 
{name:&#39;6105&#39;,value:&#39;渭南市&#39;}, 
{name:&#39;6106&#39;,value:&#39;延安市&#39;}, 
{name:&#39;6107&#39;,value:&#39;汉中市&#39;}, 
{name:&#39;6108&#39;,value:&#39;榆林市&#39;}, 
{name:&#39;6109&#39;,value:&#39;安康市&#39;}, 
{name:&#39;6110&#39;,value:&#39;商洛市&#39;} 
] 
}"; 
//data为字符串类型 则要将字符串类型转换成json数据类型
var jsondatas=eval("("+data+")");
$.each(jsondatas.root,function(i,n){
alert("name"+n.name+"value"+n.value);
}
)
//以下为数组类型字符串 转换成json 字符串 解析
//数组形式的json字符串
 var jsondata="[{name:'1',value:'0'}, {name:'6101',value:'西安市'}, {name:'6102',value:'铜川市'}, {name:'6103',value:'宝鸡市'}, {name:'6104',value:'咸阳市'}, {name:'6105',value:'渭南市'}, {name:'6106',value:'延安市'}, {name:'6107',value:'汉中市'}, {name:'6108',value:'榆林市'}, {name:'6109',value:'安康市'}, {name:'6110',value:'商洛市'}]";
var json=eval(jsondata);
$.each(json,function(i,n){
alert(json[i].name);
alert(json[i].value);//根据索引取值
});
//json数据字符 不需要转换
var json={"Products":[ 
{"orderid":"11077","customerid":"RATTC"}, 
{"orderid":"11078","customerid":"RATT"} 
], 
"Img":[{"id":"12345","url"
:"image/1.jpg"} 
]}; 
$.each(json.Products,function(i,n){
 alert(n.orderid);
})

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General processing file (Handler.ashx)

if (context.Request.QueryString["method"] != null) 
  { 
   string method = context.Request.QueryString["method"].ToString(); 
   if (method == "getlist") 
   { 
    string str = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; 
    SqlConnection conn = new SqlConnection(str); 
    conn.Open(); 
    SqlCommand cmd = new SqlCommand(); 
    cmd.Connection = conn; 
    cmd.CommandText = "select ProID,ProName,url from Project where Adress = &#39;哈尔滨&#39;"; 
    DataSet ds = new DataSet(); 
    SqlDataAdapter da = new SqlDataAdapter(cmd); 
    da.Fill(ds); 
    string sb = CreateJsonParameters(ds.Tables[0]); 
    context.Response.ClearContent(); 
    context.Response.Write(sb.ToString()); 
    context.Response.End(); 
   } 
  } 
 } 
 /// <summary> 
 /// 构建JSON字符串 
 /// </summary> 
 /// <param name="dt"></param> 
 /// <returns></returns> 
 public string CreateJsonParameters(DataTable dt) 
 { 
  System.Text.StringBuilder sb = new System.Text.StringBuilder(); 
  if (dt != null && dt.Rows.Count > 0) 
   { 
   sb.Append("["); 
   for (int i = 0; i < dt.Rows.Count; i++) 
   { 
    sb.Append("{"); 
    for (int j = 0; j < dt.Columns.Count; j++) 
    { 
     //如果值不是最后一个则添加逗号分隔 
     if (j < dt.Columns.Count - 1) 
     { 
      sb.Append("/"" + dt.Columns[j].ColumnName.ToString() + "/":" + "/"" + dt.Rows[i][j].ToString() + "/","); 
     } 
     //如果值为最后个字符则不添加逗号 
     else if (j == dt.Columns.Count - 1) 
     { 
      sb.Append("/"" + dt.Columns[j].ColumnName.ToString() + "/":" + "/"" + dt.Rows[i][j].ToString() + "/""); 
     } 
    } 
    //如果为最后一个值的话 则不添加逗号 
    if (i == dt.Rows.Count - 1) 
    { 
     sb.Append("}"); 
    } 
    else
    { 
     sb.Append("},"); 
    } 
   } 
   sb.Append("]"); 
   return sb.ToString(); 
  } 
  else { return null; } 
 }

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$.ajax
  (
  {
   type: "POST",
   url: "Handler.ashx?method=getlist",
   async: false,//true表示异步 false表示同步
   contentType: "application/json",
   dataType: &#39;json&#39;,
   success: function(result) {
   var temp=eval(result);
   //通过javascript来解析返回数组字符串
   for (var i = 0; i < temp.length; i++) 
   { 
    o.innerHTML += "项目名称:" + result[i].ProName + "<br/>网址:<a href=" + result[i].url + " mce_href=" + result[i].url + " target=&#39;_blank&#39;>" + result[i].url + "</a><br/>";
    datas += "项目名称:" + result[i].ProName + "<br/>网址:<a href=" + result[i].url + " mce_href=" + result[i].url + " target=&#39;_blank&#39;>" + result[i].url + "</a><br/>";
   }
    TINY.box.show(datas, 0, 0, 0, 1);
   }
});

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