Question

This is a strange occurrence to be sure. First off, I’m using Chrome version 23.x and have not tried to reproduce this in other browsers yet.

I receive a JSON array from the server of the form:

JSON

{
"layout":0,
"caption":"Work History",
"cols":[
   {"field":"company","label":"Company Name","hidden":false,"order":-1,"validationType":2,"list":[]},       {"field":"date_start","label":"From","hidden":false,"order":-1,"validationType":1,"list":[]},
   {"field":"date_end","label":"Until","hidden":false,"order":-1,"validationType":0,"list":[]},
   {"field":"position","label":"Title","hidden":false,"order":-1,"validationType":2,"list":[]},
   {"field":"description","label":"Description","hidden":false,"order":-1,"validationType":0,"list":[]},
   {"field":"project","label":"Project","hidden":false,"order":-1,"validationType":64,"list":[]}
   ]
}

Then, I attempt to loop over the cols objects with Javascript”

Javascript

for (var c in json.cols) {
    console.log("col name: " + c);
}

Google Chrome’s console prints the following:

Output

col name: 0
col name: 1
col name: 2
col name: 3
col name: 4
col name: 5
col name: remove

There should only be 6 outputs, first of all. Second, where does this final “remove” key come from? Why is it listed?

Answer 1

Your obj.json.cols is actually an array, not an object, so you should iterate over it with a for(;;) loop. I believe you’re looking for something like this:

for (var i=0; i<json.cols.length; i++) {
    console.log("col name: " + json.cols[i].label);
}

Furthermore, there seems to be some script messing with Array.prototype on your webpage, as with a for..in loop you should not be seeing a remove property.