Jquery ajax ie returns an error, chrome firefox normal solution

For web development, basically is under the Chrome,firefox development, then will consider IE compatibility problem, because IE developer tools, bad use. For the normal under Chrome,firefox and in IE bad use of the situation, but also to calm down a bit, this is the developer will inevitably encounter problems. Next, Ajax in Chrome,firefox under normal use, IE (IE8) under the abnormal 2 kinds of common situation.

1, the cache problem, Ajax submitted to a URL, the first normal, second or first content, the common solution is to add a random number after the URL, or timestamp.

2,php Header Setup Issue

Header ("content-type:text/html;   Charset=utf8 "); The header is added to the top of PHP to return the data text type

$.ajax ({
Type: "POST",
Url:url,
Data: ' domain= ' +$ (obj). attr ("Alt"),
DataType: "JSON", in//JS code, the settings return data to JSON, which conflicts with PHP above.
...........................

In this case, IE is not recognized, the request is 200, but the return data is Null,chrome Firefox normal. The simplest solution is to remove the content-type.
If this is the case, Ie,chrome,firefox will have any return value, try it yourself

Header ("Content-type:application/json; Charset=utf8 ");  //php the top of the header, returns the data JSON type  
 
 $.ajax { 
 type:" POST ", 
 url:url, 
 data: ' domain= ' +$ (obj). attr (" alt "), 
 datatype:" Text ",    //js code, set the return data to text, which conflicts with PHP above."