Why do javascript objects output as "undefined" when looping through an array?
javascript
Solution
The `for ... in` loop in JavaScript gives you the keys in the object, not the values.
You really should use a numeric index however:
for (var date = 0; date < dates.length; ++date) {
alert("date " + date + " is: " + dates[date]);
}
Iterating over keys with `for ... in` will not pick up only the numerically-indexed array elements; it operates on arrays as if they are plain ordinary objects. Other properties will be picked up too, plus you're not even guaranteed it'll go in ascending numeric order!
Problem
You can see a working example here: http://jsfiddle.net/bwhitney/ZDHp4/1/ I am trying to create an array of objects in javascript. When I attempt to access the objects I am getting "undefined" output. Here is some sample code: ``` var dates = []; var beginDate1 = new Date("01 / 01 / 01"); var endDate1 = new Date("02 / 02 / 02"); var beginDate2 = new Date("03 / 03 / 03"); var endDate2 = new Date("04 / 04 / 04"); // this outputs the correct dates alert("before: " + beginDate1 + "--" + endDate1); alert("before: " + beginDate2 + "--" + endDate2); dates.push({ "beginDate": beginDate1, "endDate": endDate1 }, { "beginDate": beginDate2, "endDate": endDate2 }); var date; for (date in dates) { // this outputs "date: undefined--undefined" // why would that be? alert("after: " + date.beginDate + "--" + date.endDate); } ```