I have an object I'm trying to populate from another object (that is, iterate over a return object to produce an object with only selected values from the original). My code looks like this:
var collect = {};
function getHistoricalData(username){
$.getJSON("http://url/" + username + ".json?params",
function(data){
for (var i=0; i < data.length; i++) {
console.log(i);
collect = { i : {text : data[i].text}};
$("#wrap").append("<span>" + data[i].text + "</span><br />");
};
console.log(collect);
});
}
So I'm using Firebug for debugging, and here's what I know:
console.log(i);
is showing the numbers 1-20 as expected When I log the collect
object at the end, it's structure is this: var collect = { i : {text : "the last iteration's text"}};
So the incrementer is "applying" to the data[i].text and returning the text value, but it's not doing what I expected, which is create a new member of the collect object; it's just overwriting collect.i
20 times and leaving me with the last value.
Is there a different syntax I need to be using for assigning object members? I tried collect.i.text =
and collect[i].text =
and the error was that whatever I tried was undefined.
I'd love to know what's going on here, so the more in-depth an explanation the better.
Thanks!
The reason you're seeing only one property in the object at the end is that you're not augmenting it in each loop iteration - you're overwriting it.
collect = { i : {text : data[i].text}};
This says: create an object with one property, i
, whose value is another object with one property, text
, and assign it to the variable collect
. What you want to do instead is set a property of the existing collect
object for each value of i
, where i
is the name of the property.
In order to create an object property where the name is set dynamically, you must use array-style syntax, like this: collect[i]
. I don't think you can mix array syntax and object literal syntax like you've tried. Try this instead (disclaimer, not tested):
collect[i] = { text: data[i]["text"] };
collect[i] = {text : data[i].text};
If you use collect[i].text
, since collect[i]
does not exist before the assignment, it will return undefined
, which has no text
property.
Also:
collect.i
means collect["i"]
. This is totally different from collect[i]
. .push
. As you already know, the problem is in this line:
collect = { i : {text : data[i].text}};
Every iteration of the loop, you are erasing the collect object and assigning it a new object as value. That's why in the end it only shows the last iteration.
Try this:
collect[i] = {text : data[i].text};
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