Jquery.ajax中dataType不可少

官方关于这个参数的解释:

dataType (default: Intelligent Guess (xml, json, script, or html))

Type: String

The type of data that you're expecting back from the server. If none is specified, jQuery will try to infer it based on the MIME type of the response (an XML MIME type will yield XML, in 1.4 JSON will yield a JavaScript object, in 1.4 script will execute the script, and anything else will be returned as a string). The available types (and the result passed as the first argument to your success callback) are:

• "xml": Returns a XML document that can be processed via jQuery.
• "html": Returns HTML as plain text; included script tags are evaluated when inserted in the DOM.
• "script": Evaluates the response as JavaScript and returns it as plain text. Disables caching by appending a query string parameter, "_=[TIMESTAMP]", to the URL unless the cache option is set to true. Note: This will turn POSTs into GETs for remote-domain requests.
• "json": Evaluates the response as JSON and returns a JavaScript object. In jQuery 1.4 the JSON data is parsed in a strict manner; any malformed JSON is rejected and a parse error is thrown. (See json.org for more information on proper JSON formatting.)
• "jsonp": Loads in a JSON block using JSONP. Adds an extra "?callback=?" to the end of your URL to specify the callback. Disables caching by appending a query string parameter, "_=[TIMESTAMP]", to the URL unless the cache option is set to true.
• "text": A plain text string.
• multiple, space-separated values: As of jQuery 1.5, jQuery can convert a dataType from what it received in the Content-Type header to what you require. For example, if you want a text response to be treated as XML, use "text xml" for the dataType. You can also make a JSONP request, have it received as text, and interpreted by jQuery as XML: "jsonp text xml." Similarly, a shorthand string such as "jsonp xml" will first attempt to convert from jsonp to xml, and, failing that, convert from jsonp to text, and then from text to xml.

php文件如下:

<?php
header("Content-Type:text/html;charset=utf-8");

echo json_encode(array("hello","world");

?>

$.ajax({
url:"lib3/grabBaiduBaike.php",
type:"GET",

data:{q:queryValue},
error: function(){
alert('载入数据失败，服务器可能遇到故障');
},
beforeSend:loading,
success:function(data){ 

console.log(data);
var str1=data[0];
var str2=data[1];
console.log(typeof data);
console.log(str1);
console.log(str2);

}
});

你会发现str1是h，str2为e，与想象的结果不符，这是为什么。

因为php的header中已经说明这是text/html类型，jquery把返回过来的数据就当做字符串串来处理了，加上：

dataType:'json',

就正常了。