Uncaught TypeError: Cannot use 'in' operator to search for 'length' in

问题

Uncaught TypeError: Cannot use 'in' operator to search for 'length' in "

This is the error I receive when I try to do a $.each to this JSON object :

{"type":"Anuncio","textos":["Probando esto","$ 20150515"],"submit":"codParameters?___DDSESSIONID\u003d14EA4721A904D6DD71591156996E29F7%3A%2FMobilTest"}

I have also tried to do the same with stringify, but I receive the same error:

{\"type\":\"Anuncio\",\"textos\":[\"Probando esto\",\"$ 20150515\"],\"submit\":\"codParameters?___DDSESSIONID\\u003d06CBEC9D1A53616EFF703A8C71FBC2B4%3A%2FMobilTest\"}"

If I remove parameters ___DDSESSIONID\\u003d06CBEC9D1A53616EFF703A8C71FBC2B4%3A%2FMobilTest from the object the $.each works fine.

Why might this be happening?

Thanks in advance.

回答1:

The in operator only works on objects. You are using it on a string. Make sure your value is an object before you using $.each. In this specific case, you have to parse the JSON:

$.each(JSON.parse(myData), ...);

回答2:

maybe you forget to add parameter dataType:'json' in your $.ajax

$.ajax({
   type: "POST",
   dataType: "json",
   url: url,
   data: { get_member: id },
   success: function( response ) 
   { 
     //some action here
   },
   error: function( error )
   {
     alert( error );
   }
});

来源：https://stackoverflow.com/questions/30269461/uncaught-typeerror-cannot-use-in-operator-to-search-for-length-in