javascript 如何将 JSON 从本地 url 设置为变量
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How can I set JSON into a variable from a local url
提问by Chase Florell
Evidently jQuery has made me dumb.
显然 jQuery 让我变得愚蠢。
I've got a local url that serves up raw JSON, and I can't figure out how to consume that json from within my method without using jQuery.
我有一个提供原始 JSON 的本地 url，我无法弄清楚如何在不使用 jQuery 的情况下从我的方法中使用该 json。
Here's how I know to do it WITH jQuery
这是我知道如何使用 jQuery 做到这一点
var myJson;
$.getJSON('/local/path/to/json', function (data) {
myJson = data;
});
// Now I can use myJson in a method.
回答by Jonathan M
To retrieve the JSON string from a server use XMLHttpRequestobject as described in this reference:
要从服务器使用XMLHttpRequest对象中检索 JSON 字符串，如本参考中所述：
http://developer.mozilla.org/en/XMLHttpRequest
http://developer.mozilla.org/en/XMLHttpRequest
You'll find that it's quite involved with all the unseen things you need to account and check for. Thus libraries like jQuery.
你会发现它涉及到你需要考虑和检查的所有看不见的东西。因此像jQuery这样的库。
To convert the JSON string to a javascript object, use JSON.parse(). Here's the reference:
要将 JSON 字符串转换为 javascript 对象，请使用JSON.parse(). 这是参考：
http://developer.mozilla.org/En/Using_native_JSON
http://developer.mozilla.org/En/Using_native_JSON
Here's an example:
下面是一个例子：
function readJSON(file) {
var request = new XMLHttpRequest();
request.open('GET', file, false);
request.send(null);
if (request.status == 200)
return request.responseText;
};
var myObject = JSON.parse(readJSON('/local/path/to/json'));
EDIT #2: Thanks for editing in this example, Chase. A word of warning. It is not a good idea to make the open()method a synchronous call by using falsein the 3rd parm. AJAX is intentionally designed for asynchronous use, and to make a synchronous call invites lock ups. As one who used to think there was a place for synchronous calls, I now find there's always a better way to get it done asynchronously. Word to the wise.
编辑 #2：感谢您在此示例中进行编辑，Chase。一句警告。open()通过false在第三个参数中使用使方法成为同步调用并不是一个好主意。AJAX 是专门为异步使用而设计的，并且进行同步调用会导致锁定。作为曾经认为有一个地方可以进行同步调用的人，我现在发现总有一种更好的方法可以异步完成它。对智者说。
回答by ThinkingStiff
I you're familiar with jQuery, this is a drop-in replacement for $.ajax:
我熟悉 jQuery，这是一个替代品$.ajax：
Script:
脚本：
function ajax( uri, settings ) {
var ajax = new window.XMLHttpRequest(),
data = settings.type == 'GET' ? '' : settings.data,
async = settings.async ? settings.async : false;
uri = settings.type == 'GET' ? uri + ( settings.data ? '?' + settings.data : '' ) : uri;
ajax.onreadystatechange = function () {
if ( ajax.readyState == 4 ) { //response ready
if ( ajax.status == 200 ) { //success
if ( settings.success ) settings.success( ajax.responseText, ajax.statusText );
if ( settings.complete ) settings.complete( ajax, ajax.statusText );
} else {
if ( settings.error ) settings.error( ajax, ajax.status, ajax.statusText );
};
};
};
ajax.open( settings.type, uri, async );
if ( settings.headers ) {
for ( var header in settings.headers ) {
ajax.setRequestHeader( header, settings.headers[header] );
};
};
ajax.send( data );
};
Call it just like jQuery:
像 jQuery 一样调用它：
ajax( '/local/path/to/json', {
"type": "GET", //or "POST"
//"data": "<query string>", //if POST
"success": function ( data, status ) {
var myJson = window.JSON.parse( data );
},
"error": function ( response, status, error ) {
// handle error
}
} );
回答by Elias Hossain
Please have a look at be below code snap which will on in all browsers, thanks
请看下面的代码快照，它将在所有浏览器中打开，谢谢
function getJSONData(jsonurl) {
var req = null;
if (window.XMLHttpRequest) {
req = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
try {
req = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e) {
try {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) { }
}
}
req.open('GET', jsonurl, false);
req.send(null);
return req.status == 200 ? req.responseText : 'Error occurred';
}
var jsonData = JSON.parse(getJSONData('/local/path/to/json'));
alert(getJSONData('/local/path/to/json'));
Hope this will be very helpful, thanks for your time
希望这会很有帮助，感谢您的时间
