GET請求到REST API

http://www.serveraddress.com/api/users/1是有效的，值是正確的JSON格式。GET請求到REST API

的JSON：

{ 
    "id":1, 
    "name":"Ryan Chenkie", 
    "email":"[email protected]", 
    "battles_won":0, 
    "created_at":"2017-02-25 19:20:58", 
    "updated_at":"2017-02-25 19:20:58", 
    "blobs":[ 
     { 
     "id":1, 
     "name":"Blob 1", 
     "type":"type A", 
     "color":"red", 
     "alive":1, 
     "level":1, 
     "exercise_level":-302, 
     "cleanliness_level":-302, 
     "health_level":-302, 
     "owner_id":1, 
     "created_at":"2017-02-25 19:20:58", 
     "updated_at":"2017-02-26 01:23:05" 
     }, 
     { 
     "id":5, 
     "name":"Blob 5", 
     "type":"type C", 
     "color":"blue", 
     "alive":1, 
     "level":1, 
     "exercise_level":-302, 
     "cleanliness_level":-302, 
     "health_level":-302, 
     "owner_id":1, 
     "created_at":"2017-02-25 19:20:58", 
     "updated_at":"2017-02-26 01:23:05" 
     } 
    ] 
}

當我嘗試運行的getUser（），我得到一個SyntaxError: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data。

我的代碼有什麼問題？我的setRequestHeader不正確？

getUser(1); 

function getUser(userId) { 
    var usersUrl = "http://www.serveraddress.com/api/users/"; 
    var params = userId; 
    var xhttp = new XMLHttpRequest(); 
    xhttp.open("GET", usersUrl + params, true); 
    xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); 
    xhttp.send(); 
    var response = JSON.parse(xhttp.responseText); 

    return response;

}

來源

2017-02-26 falafel

什麼是導致JSON？我想這裏有一個錯誤。 – Psi

@Psi我編輯了OP來包含JSON。我檢查了一個JSON格式化程序，它說它是有效的JSON。 – falafel

檢查瀏覽器工具或提琴手的響應。確保它實際上獲得了該JSON作爲迴應。 – JLRishe

因爲XMLHttpRequest是異步的，函數返回response（它是空的）時，即使發送請求之前。
要獲取responseText的請求完成後，使用被稱爲一個回調函數，當事件的load事件觸發：

function getUser(userId, callback) { 
 
    var usersUrl = "http://www.serveraddress.com/api/users/"; 
 
    var params = userId; 
 
    var xhttp = new XMLHttpRequest(); 
 
    
 
    xhttp.addEventListener('load', callback); 
 
    xhttp.addEventListener('error',() => console.log("Request to "+usersUrl+params+" failed")); 
 
    
 
    xhttp.open("GET", usersUrl + params, true); 
 
    xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); 
 
    xhttp.send(); 
 
} 
 
getUser(1, function() { 
 
    console.log(JSON.parse(this.responseText)); 
 
});

來源

2017-02-26 03:59:25

GET請求到REST API

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