Create variables based on array

Question

I have the following array and a loop fetching the keys (https://jsfiddle.net/ytm04L53/)

var i;
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];

for (i = 0; i < feeds.length; i++) {
    var feed = feeds[i];
    alert(feed.match(/\d+$/));
}

The array will always contain different number of keys, What I would like to do is either use these keys as variables and assign the value after the : semicolon as its value or just create a new set of variables and assign the values found on these keys to them.

How can I achieve this? so that I can then perform some sort of comparison

if (test_user > 5000) {dosomething}

update Thanks for the answers, how can I also create a set of variables and assign the array values to them? For instance something like the following.

valCount(feeds.split(","));

    function valCount(t) {
     if(t[0].match(/test_user_.*/))
      var testUser = t[0].match(/\d+$/);
     }

Obviously there is the possibility that sometimes there will only be 1 key in the array and some times 2 or 3, so t[0] won't always be test_user_

I need to somehow pass the array to a function and perform some sort of matching, if array key starts with test_user_ then grab the value and assign it to a define variable.

Thanks guys for all your help!

Sorry didnt understand but what are you trying to do? Assign new values to the keys? — code
– code, Commented Aug 26, 2015 at 16:36
Use an object, not dynamically named variables. The latter is prone to all sorts of unexpected failures and security vulnerabilities. — dsh
– dsh, Commented Aug 26, 2015 at 16:38

T.J. Crowder · Accepted Answer · 2015-08-26 16:38:09Z

2

You can't (reasonably) create variables with dynamic names at runtime. (It is technically possible.)

Instead, you can create object properties:

var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];

var obj = {};
feeds.forEach(function(entry) {
    var parts = entry.split(":"); // Splits the string on the :
    obj[parts[0]] = parts[1];     // Creates the property
});

Now, obj["test_user_201508_20150826080829.txt"] has the value "12345".

Live Example:

var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];

var obj = {};
feeds.forEach(function(entry) {
    var parts = entry.split(":");
    obj[parts[0]] = parts[1];
});
snippet.log(obj["test_user_201508_20150826080829.txt"]);

<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

answered Aug 26, 2015 at 16:38

T.J. Crowder

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2 Comments

David Garcia Over a year ago

Thanks very much for your code, in any case, if I wanted to assign the values to static variables, how can I achieve this? please see my updated question.

T.J. Crowder Over a year ago

@J.D: "...if I wanted to assign the values to static variables..." You don't. :-) I know you think you do, but that road is just (to use an 80s word) gnarly. The code to do it is convoluted, error-prone, has poor performance, is difficult to maintain, and most importantly of all is unnecessary. Using an object (or an array) is the right way to handle this kind of dynamic situation. The update to your question shows you assigning to a testUser variable, but as you flagged up, there would need to be a dynamic number of them. That's what objects and arrays are for.

Starfish · Accepted Answer · 2015-08-26 16:37:21Z

1

You can do it like this, using the split function:

var i;
var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];

for (i = 0; i < feeds.length; i++) {
    var feed = feeds[i];
    console.log(feed.split(/[:]/));
}

This outputs:

["test_user_201508_20150826080829.txt", "12345"]
["test_user_list20150826", "666"]
["test_list_Summary20150826.txt", "321"]

answered Aug 26, 2015 at 16:37

Starfish

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Comments

Jacob Petersen · Accepted Answer · 2015-08-26 16:38:28Z

1

Use the split method

var feeds = ["test_user_201508_20150826080829.txt:12345","test_user_list20150826:666","test_list_Summary20150826.txt:321"];

feedMap = {}
for (i = 0; i < feeds.length; i++) {
    var temp = feeds[i].split(':');
    feedMap[temp[0]] = temp[1];
}

Yields:

{
    "test_user_201508_20150826080829.txt":"12345",
    "test_user_list20150826":"666",
    "test_list_Summary20150826.txt":"321"
}

And can be accessed like:

feedMap["test_user_201508_20150826080829.txt"]

Here is a codepen

answered Aug 26, 2015 at 16:38

Jacob Petersen

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Comments

m.antkowicz · Accepted Answer · 2015-08-26 16:58:41Z

1

it is not very good idea but if you really need to create variables on-the-run here's the code:

for (i = 0; i < feeds.length; i++) 
{
    var feed = feeds[i];
    window[feed.substring(0, feed.indexOf(":"))] = feed.match(/\d+$/);
}

alert(test_user_201508_20150826080829)

Of course you cannot have any variable-name-string containing banned signs (like '.')

Regards, Michał

edited Aug 26, 2015 at 16:58

answered Aug 26, 2015 at 16:42

m.antkowicz

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