<script type="text/javascript">
var ar = [];
ar["index"].push("data1");
ar["index"].push("data2");
ar["index3"].push("data5");
ar[55].push("data7");
console.log(ar);
</script>
I get: TypeError: ar.index is undefined
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possible duplicate of how to push associative item into array in javascript?Bik– Bik2015-02-16 13:53:33 +00:00Commented Feb 16, 2015 at 13:53
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5 Answers
with this
ar["index"].push("data1");
javascript tries to push "data1" into an array. The problem is that it expects an array, which ar["index"] is not as it is undefined.
You first need to initialize it
ar["index"] = [];
ar["index"].push("data1");
push() documentation here
Comments
Try this :-
<script type="text/javascript">
var ar = [];
ar["index"] = data1;
ar["index"] = data2;
.........
........
console.log(ar);
</script>
3 Comments
Sirko
In this case, this should be an object and not an array.
Bik
No this will also work for array ..........you can check jsfiddle.net/7j5om9ee
Sirko
It will work for an array, but not in every way intended. So for example
ar.length will still be 0 after your assignment. Array is just a special case of an object. If you do not use any of the added methods, just use a plain object.Array accepts the method push
What you wanna do is direct access, like a dictionary style... in this case, setting will just do the trick.
var ar = [];
ar["index"] = "data1";
Comments
just make it like
<script type="text/javascript">
var ar = [];
ar.push("data1");
ar.push("data2");
ar.push("data5");
ar.push("data7");
console.log(ar);
</script>
Here is dev reference api => link
2 Comments
Sirko
The second approach should use an object instead of an array.
Jenish Rabadiya
@ShirAzi then
all_line_path[data.line_id] should return array.If you're trying create an array of arrays you must check that the "inner" array exists. Something along the lines of this:
if(ar['index'] == null) {
ar['index'] = [];
ar['index'].push("data1");
} else {
ar['index'].push("data1");
}
