Converting a string to a javascript associative array

Question

I have a string

string = "masterkey[key1][key2]";

I want to create an associative array out of that, so that it evaluates to:

{
  masterkey: {
    key1: {
      key2: value
    }
  }
}

I have tried this:

var fullName = string;
fullName = fullName.replace(/\[/g, '["');
fullName = fullName.replace(/\]/g, '"]');
eval("var "+fullName+";");

But I get the error: missing ; before statement with an arrow pointing to the first bracket in ([) "var masterkey["key1"]["key2"];"

I know that eval() is not good to use, so if you have any suggestions, preferably without using it, I'd really appreciate it!

Welcome (back?) to Stack Overflow! When you were writing your question, to the right there was a handy How to Format box, and above the text area a [?] button. Both are worth a read. The fourth bullet point in How to Format tells you how to mark up code so it displays correctly. — T.J. Crowder
– T.J. Crowder, Commented Feb 9, 2012 at 9:08
FYI: "associative arrays" in Javascript are objects. Arrays are never associative in Javascript. — deceze
– deceze ♦, Commented Feb 9, 2012 at 9:11

Yoshi · Accepted Answer · 2012-02-09 09:22:51Z

4

Not the most beautiful, but it worked for me:

var
  path = "masterkey[key1][key2]",
  scope = {};

function helper(scope, path, value) {
  var path = path.split('['), i = 0, lim = path.length;
  for (; i < lim; i += 1) {
    path[i] = path[i].replace(/\]/g, '');

    if (typeof scope[path[i]] === 'undefined') {
      scope[path[i]] = {};
    }

    if (i === lim - 1) {
      scope[path[i]] = value;
    }
    else {
      scope = scope[path[i]];
    }
  }
}

helper(scope, path, 'somevalue');

console.log(scope);

demo: http://jsfiddle.net/hR8yM/

answered Feb 9, 2012 at 9:22

Yoshi

54.7k14 gold badges92 silver badges107 bronze badges

+1 Seems fine. Maybe provide a JSFiddle so we can see that it actually is all right. :)

Robert Koritnik
– Robert Koritnik

02/09/2012 09:25:48
Commented Feb 9, 2012 at 9:25

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georg · Accepted Answer · 2012-02-09 09:54:55Z

1

function parse(s, obj) {
    s.match(/\w+/g).reduce(function(o, p) { return o[p] = {} }, obj);
    return obj;
}

console.dir(parse("masterkey[key1][key2]", {}))

answered Feb 9, 2012 at 9:54

georg

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Mujtaba Haider · Accepted Answer · 2012-02-09 09:27:24Z

0

Now try this

string = "masterkey[key1][key2]";
var fullName = string;
fullName = fullName.replace(/\[/g, '[\'');
fullName = fullName.replace(/\]/g, '\']');

document.write("var "+fullName+";");

answered Feb 9, 2012 at 9:27

Mujtaba Haider

1,6502 gold badges19 silver badges29 bronze badges

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Paul Butcher · Accepted Answer · 2012-02-09 09:28:27Z

1) When using eval, the argument you provide must be valid, complete javascript.

The line

 var masterkey["key1"]["key2"];

is not a valid javascript statement.

When assigning a value to a variable, you must use =. Simply concatenating some values on to the end of the variable name will not work.

2) var masterkey = ["key1"]["key2"] doesn't make sense.

This looks like an attempt to assign the "key2" property of the "key1" property of nothing to masterkey.

If you want the result to be like the example object you give, then that is what you need to create. That said, parsing the string properly to create an object is better than using regular expressions to translate it into some script to evaluate.

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