Maintaining array order in Javascript

Question

I am new to JavaScript and I am having trouble working with my array, I want my array ordered how I explicitly write it and not how JavaScript decides it wants it.

If we

Answer 1

I don't get it. What makes you think that 0, then 4, then 2, is in any form or shape "in order"?

However, apparently what you want is to keep the number and the string together, in the order that you specify.

Your mistake, if you'll excuse me for perhaps sounding a bit harsh, is that you seem to think that you can use indices or member names to be both a means to access data and part of the data itself.

You can't, and you shouldn't. An index is an index, a name is a name, and data is data ^[1].

Here are two implementations of keeping your numbers and strings together:

var pairs = [
    [0, "zero"],
    [4, "four"],
    [2, "two"]
];
for (var index in pairs) {
    alert(pairs[index][0] + ": " + pairs[index][1]);
};

For this one, I keep the pairs of numbers and strings together in arrays of their own: the numbers at position 0, the strings at position 1. I store these arrays in pairs.

Then I iterate over array with for/in, which, in each iteration, gives me an index of my pairs array.

I then use that index to access the right sub-array in pairs, and get the number from position 0 and the string from position 1.

var pairs = [
    {number: 0, string: "zero"},
    {number: 4, string: "four"},
    {number: 2, string: "two"}
];
for (var index in pairs) {
    alert(pairs[index].number + ": " + pairs[index].string);
};

This one works exactly the same, except of storing the pairs in arrays, I store them in objects.

This has the added bonus of better readability inside the for loop: pairs[index][0] and pairs[index][1] do not really convey a clear meaning. It tells us nothing more than, "of the pair with the given index, get items 0 and 1".

However, pairs[index].number and pairs[index].name are much clearer: "of the pair with the given index, give me the number and the name."

_

Footnotes:

[1a] A number is a number: my bank account number is just that: a means to identify my bank account. It doesn't convey any meaning as to my name, my PIN, or the balance on my account -- all attributes that would qualify as data belonging to my bank account.

[1b] A name is a name: my name is just a name. When you're talking about me, you can use my name to refer to me, so that others know whom you are talking about. My name does not convey any information about my hobbies, my SSN, or what brand of car I have -- all attributes that would qualify as data that would describe certain aspects of me. (However, by convention, you can often tell a person's gender by their name)