javascript iterate through array

Question

I have an array as follows:

levelinfoarray["test"] = new Array(16,20,4,5,"Test level");
levelinfoarray[1] = new Array(29,25,17,13,"Introduction");
levelinfoarray[2] = new Array(16,24,6,4,"Counting...");
levelinfoarray[3] = new Array(16,20,4,5,"Where am I going?");
...

I want to iterate through the array and get the level number and level description like this

Test) Test level
1) Introduction
2) Counting...
3) Where am I going?
...

I have tried a for loop and a forEach, but both only give me the numbered entries. How would I get the "test" entry?

With JavaScript arrays, it's really not practical to mix numeric and non-numeric keys. Arrays are all about the numerically indexed properties. — Pointy
– Pointy, Commented Mar 1, 2014 at 0:23

Barmar · Accepted Answer · 2014-03-01 00:26:51Z

4

When an array has non-numeric keys, it's actually an object. Use for...in

for (key in levelinfoarray) {
    if (levelinfoarray.hasOwnProperty(key)) {
        console.log(key+') '+levelinfoarray[key][4]);
    }
}

P.S. don't use new Array, use array literals:

levelinfoarray["test"] = [16,20,4,5,"Test level"];

answered Mar 1, 2014 at 0:26

Barmar

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3 Comments

Pointy Over a year ago

This will work, but it's important to note that the order of property traversal is undefined.

sabof Over a year ago

An array is always an object. With strings as keys

Patrick Over a year ago

This works great, it puts the test array at the end of the list, which is fine.

sabof · Accepted Answer · 2014-03-01 00:35:35Z

1

Object.keys(levelinfoarray) // => ["1", "2", "3", "test"]

To iterate:

Object.keys(levelinfoarray).forEach(function(key) {console.log(key)});

You'll have to polyfill Object.keys and Array.prototype.forEach, if you want to support older browsers.

edited Mar 1, 2014 at 0:35

answered Mar 1, 2014 at 0:26

sabof

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