Question

如何在javaScript中访问“值的JSON表示”？我将json_encode和echo结果用于AJAX调用，我得到了PHP手册所指的json对象“json_encode - 返回值的JSON表示”。这是我控制日志变量

时得到的一个简短示例

{"RECORD_NUM":1002,"DATE_FIELD":"1747-01-19","DESCRIPTION":"Johann Bode founder of \"Bode's Law \" dies"},
{"RECORD_NUM":1111,"DATE_FIELD":"1770-01-19","DESCRIPTION":"Battle of Golden Hill (Lower Manhattan)"}]

下一步是解析＆＃34;响应＆＃34;与JSON.parse：

returnedArray=JSON.parse(response);

要在JavaScript中访问JSON对象，请使用JSON.parse（）解析它，并通过“。”或“[]”访问它。

如果JSON.parse失败，就像在我的情况下那样，我会问一个问题“你怎么能不能访问返回的值的JSON表示。”？“ 这是一个小的html文件，我通过声明一个javaScript变量但没有“值的JSON表示”来测试。这个文件按预期工作

<!DOCTYPE html><html>
<head>
    <title>JSON value</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
    <div>TODO write content</div>
    <!--Call a javaScript-->
    <script type="text/javascript" src="js/jquery-2.2.0.min.js"></script>
    <script>
        $("document").ready(function () {
            var response = [
                {"RECORD_NUM": 967, "DATE_FIELD": "1736-01-19", "DESCRIPTION": "James Watt, inventor of the steam engine, was born in Scotland."},
                {"RECORD_NUM": 1002, "DATE_FIELD": "1747-01-19", "DESCRIPTION": "Johann Bode founder of \"Bode's Law \" dies"},
                {"RECORD_NUM": 1111, "DATE_FIELD": "1770-01-19", "DESCRIPTION": "Battle of Golden Hill (Lower Manhattan)"}
            ];
            dataCheck = response[0].DATE_FIELD;
            console.log("dataCheck = " + dataCheck + "\n");
        });
    </script>
</body>
</html>

控制台打印：

dataCheck = 1736-01-19

如果我在AJAX成功通话中使用上面的代码，我会收到错误：

            success: function (response) {
            console.log("Returned data = RESPONSE: \n" + response + "\n\n");
             dataCheck = response[0].DATE_FIELD;
            console.log("dataCheck = " + dataCheck + "\n");

控制台日志：

queryDatabase02.js:39 Returned data = RESPONSE: 
[{"RECORD_NUM":967,"DATE_FIELD":"1736-01-19","DESCRIPTION":"James Watt, inventor of the steam engine, was born in Scotland."},
{"RECORD_NUM":1002,"DATE_FIELD":"1747-01-19","DESCRIPTION":"Johann Bode founder of \"Bode's Law \" dies"},
{"RECORD_NUM":1111,"DATE_FIELD":"1770-01-19","DESCRIPTION":"Battle of Golden Hill (Lower Manhattan)"},
        ...
}]

所以问题是，＆＃34;如何在javaScript中访问“值的JSON表示”？＆＃34; 答案 - ＆＃34;你不能＆＃34;？

在检查PHP文件中只有一个echo并且还发送头文件后，我发现在echo json_encoded之前删除了头文本不会导致错误。这是PHP文件的结尾：

// json_encode — Returns the JSON representation of a value
$jsonVal = json_encode($timeRtr);
$fileHandle = fopen('storage\jsonStorage', "a") or die("Unable to open file!");
fwrite($fileHandle, $jsonVal);
fwrite($fileHandle, "\n");
fclose($fileHandle);
//header('Content-Type: application/json');
echo ($jsonVal);

＆GT？; 这是javascript文件queryDataBase02.js

$("document").ready(function () {
$("button[name='History']").click(function (e) {
    // so the form does not get submitted
    e.preventDefault();
    var displayStr = "";
    var theQuery = {queryString: "SELECT * FROM time_table WHERE" +
                " EXTRACT(MONTH FROM DATE_FIELD ) = DATE_FORMAT(NOW()," +
                " '%c')  AND  EXTRACT(DAY FROM DATE_FIELD ) = DATE_FORMAT    (NOW     (), '%e')" +
                " ORDER BY DATE_FIELD]}"};
    console.log("\t THEObject = " + theQuery + "\n");
    $.ajax({
        type: "POST",
        //                   dataType: "json",
        url: "queryDatabase02.php",
        data: theQuery,
        success: function (response) {
            console.log("Returned data = RESPONSE: \n" + response + "\n\n");
            dataCheck = response[0].DATE_FIELD;
            console.log("dataCheck on response " + dataCheck + " \n");


            // How big is response
            responseCnt = response.length;
            console.log("responseCnt = " + responseCnt + "\n");

            // Access the data ...
            displayArray = JSON.parse(response);
            console.log("THIS IS display STRING:\n" + displayArray + "\n");
            dataCheck = displayArray[0].DATE_FIELD;
            console.log("dataCheck Second time = " + dataCheck + "\n");
            console.log("LEAVING .............\n");
        }
    });
    return false;
    });
});

这是在PHP文件中有和没有标题的控制台输出。

WITH -- "header('Content-Type: application/json');"

queryDatabase02.js:10    THEObject = [object Object]
queryDatabase02.js:17 Returned data = RESPONSE: 
[object Object],[object Object],[object Object],[object Object],
[object Object],[object Object],[object Object],[object Object],
[object Object],[object Object],[object Object],[object Object],
[object Object],[object Object],[object Object],[object Object],
[object Object],[object Object],[object Object],[object Object],
[object Object],[object Object],[object Object],[object Object],
[object Object],[object Object],[object Object],[object Object]

queryDatabase02.js:19 dataCheck on response 1736-01-19 
queryDatabase02.js:24 responseCnt = 28
VM211:1 Uncaught SyntaxError: Unexpected token o
$.ajax.success  @   queryDatabase02.js:27
i   @   jquery-2.2.0.min.js:2
j.fireWith  @   jquery-2.2.0.min.js:2
z   @   jquery-2.2.0.min.js:4
(anonymous function)    @   jquery-2.2.0.min.js:4
==========================================================

没有 - ＆＃34;标题（＆＃39;内容类型：application / json＆＃39;）;＆＃34;

 THEObject = [object Object]

queryDatabase02.js:17 Returned data = RESPONSE: 
[{"RECORD_NUM":967,"DATE_FIELD":"1736-01-19","DESCRIPTION":"James Watt,         inventor of the steam engine, was born in Scotland."},
{"RECORD_NUM":1002,"DATE_FIELD":"1747-01-19","DESCRIPTION":"Johann Bode         founder of \"Bode's Law \" dies"},
{"RECORD_NUM":1111,"DATE_FIELD":"1770-01-19","DESCRIPTION":"Battle of     Golden     Hill (Lower Manhattan)"},
....
"}]


queryDatabase02.js:19 dataCheck on response undefined 

queryDatabase02.js:24 responseCnt = 4948

queryDatabase02.js:28 THIS IS display STRING:
[object Object],[object Object],[object Object],[object Object],[object         Object],
[object Object],[object Object],[object Object],[object Object],[object         Object],
[object Object],[object Object],[object Object],[object Object],[object Object],

.... [object Object]

queryDatabase02.js:30 dataCheck Second time = 1736-01-19

queryDatabase02.js:31 LEAVING .............

最后，我注意到有和没有来自PHP文件的头信息的记录计数差异。

您可以使用javaScript访问值的JSON表示吗？

0 个答案: