如何在Jquery中遍历对象？

Question

I am getting TypeError: field[i] is undefined from this:

function ObserverFetch() {

               $.ajax({
                   type: "POST",
                   url: "Observer.aspx/ObserverFetch",
                   data: JSON.stringify({ id: "" }),
                   contentType: "application/json; charset=utf-8",
                   dataType: "json",
                   async: true,
                   success: function (data, status) {

                       $.each(data, function (i, field) {

                           alert(field[i].BidderName);
                           //$('#dvBids').text(field);
                           //$("#gvDetails").append("<tr><td>" + field.SrNo + "</td><td>" + field.BidderName + "</td><td>" + field.BidAmt + "</td></tr>");
                       });                     
                   },
                   failure: function (data) {
                       alert(data.d);
                   },
                   error: function (data) {
                       alert(data.d);
                   }
               });
       }

This is what I get in field

[{"SrNo":4,"BidderName":"faisal","BidAmt":6000000.0000,"BidDate":"\/Date(1430199508063)\/"},{"SrNo":3,"BidderName":"arbaaz jalil","BidAmt":5000010.0000,"BidDate":"\/Date(1430199494083)\/"},{"SrNo":2,"BidderName":"arbaaz","BidAmt":500000.0000,"BidDate":"\/Date(1430199483530)\/"},{"SrNo":1,"BidderName":"shekhar1","BidAmt":5000.0000,"BidDate":"\/Date(1430199394957)\/"}]

$('#dvBids').text(JSON.stringify(data)); gives me :

{"d":"[{\"SrNo\":4,\"BidderName\":\"faisal\",\"BidAmt\":6000000.0000,\"BidDate\":\"\\/Date(1430199508063)\\/\"},{\"SrNo\":3,\"BidderName\":\"arbaaz jalil\",\"BidAmt\":5000010.0000,\"BidDate\":\"\\/Date(1430199494083)\\/\"},{\"SrNo\":2,\"BidderName\":\"arbaaz\",\"BidAmt\":500000.0000,\"BidDate\":\"\\/Date(1430199483530)\\/\"},{\"SrNo\":1,\"BidderName\":\"shekhar1\",\"BidAmt\":5000.0000,\"BidDate\":\"\\/Date(1430199394957)\\/\"}]"}

$.each(data.d , function (i, field) { gives me :

TypeError: invalid 'in' operand a

Answer 1

Bizarrely, the response from your server is a JSON object with a single property, d , which is a string containing the JSON for an array. If it's your server method generating that response, you probably want to adjust it so that data.d is an array, not a string.

To get those results and loop through them, you'll need to parse it, and then use field directly rather than via i :

var fields = JSON.parse(data.d);
$.each(fields, function(i, field) {
    alert(field.BidderName);
});

or of course:

$.each(JSON.parse(data.d), function(i, field) {
    alert(field.BidderName);
});

---

Side note: As the parsed version of data.d is an array, on any modern browser you can use Array#forEach rather than $.each , which has a slightly less-confusing argument list for the callback. ( Array#forEach can be easily polyfilled on IE8 and earlier.)

JSON.parse(data.d).forEach(function(field) {
    alert(field.BidderName);
});

---

Live Example of both:

 var data = { "d": "[{\\"SrNo\\":4,\\"BidderName\\":\\"faisal\\",\\"BidAmt\\":6000000.0000,\\"BidDate\\":\\"\\\\/Date(1430199508063)\\\\/\\"},{\\"SrNo\\":3,\\"BidderName\\":\\"arbaaz jalil\\",\\"BidAmt\\":5000010.0000,\\"BidDate\\":\\"\\\\/Date(1430199494083)\\\\/\\"},{\\"SrNo\\":2,\\"BidderName\\":\\"arbaaz\\",\\"BidAmt\\":500000.0000,\\"BidDate\\":\\"\\\\/Date(1430199483530)\\\\/\\"},{\\"SrNo\\":1,\\"BidderName\\":\\"shekhar1\\",\\"BidAmt\\":5000.0000,\\"BidDate\\":\\"\\\\/Date(1430199394957)\\\\/\\"}]" }; snippet.log("Using $.each:"); $.each(JSON.parse(data.d), function(i, field) { snippet.log(field.BidderName); }); snippet.log("----"); snippet.log("Using forEach"); JSON.parse(data.d).forEach(function(field) { snippet.log(field.BidderName); }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 --> <script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script> 

Answer 2

The problem is that in var fiel you already have a each element of the array. The solutiobn is:

$.each( obj, function (i, field) {
  alert(field.BidderName );
});