string as object reference to object variable

Question

var string = 'object.data.path';

That's a string that resembles a path to variable.

How can I return the corresponding variable from that string?

Something like transforming the string into return object.data.path;

The thing behind this is that the string could be much longer (deeper), like:

var string = 'object.data.path.original.result';

Where is the string coming from? – Dennis Sep 28 '11 at 13:01 — Dennis, Sep 28 '11 at 13:01
HTML5 data attribute name, dashes replaced with dots. – tomsseisums Sep 28 '11 at 13:07 — tomsseisums, Sep 28 '11 at 13:07

score 3 · Accepted Answer · answered Sep 28 '11 at 13:07

3

function GetPropertyByString(stringRepresentation) {
    var properties = stringRepresentation.split("."),
        myTempObject = window[properties[0]];
    for (var i = 1, length = properties.length; i<length; i++) {
    myTempObject = myTempObject[properties[i]];
    }

    return myTempObject;
}


alert(GetPropertyByString("object.data.path"));

this assumes that your first level object (in this case called object is global though. Alternatively, although not recommended, you could use the eval function.

answered Sep 28 '11 at 13:07

Dennis

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Thanks! Already made a similar function, but asked in hope that there's a different way except loops.. – tomsseisums Sep 28 '11 at 13:13
For each iteration, you should check if `myTempObject` is still an object, and only then retrieve its property... – Šime Vidas Sep 28 '11 at 13:38

score 3 · Answer 2 · answered Sep 28 '11 at 13:11

3

Assuming you don't want to just use eval you could try something like this:

function stringToObjRef(str) {
   var keys = str.split('.'),
       obj = window;
   for (var i=0; i < keys.length; i++) {
      if (keys[i] in obj)
         obj = obj[keys[i]];
      else
         return;
   }

   return obj;
}

console.log(stringToObjRef('object.data.path.original.result'));

Uses a for loop to go one level down at a time, returning undefined if a particular key in the chain is undefined.

answered Sep 28 '11 at 13:11

nnnnnn

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Thanks, award given to Chips_100 due to lower reputation. A bonus tho' for undefined return. – tomsseisums Sep 28 '11 at 13:14
Thanks. (Must've been that extra time I spent thinking about the undefined test that let Chips_100 answer before me.) Regarding your comment to Chips about looking for a way to do it without loops, you can do it with function recursion... – nnnnnn Sep 28 '11 at 13:19
Function recursion is still a loop, just, not a "documented" one. – tomsseisums Sep 28 '11 at 13:25
1

Yeah, I know. And for this purpose I think a standard for loop is simpler. Some more reading that I just found from the related list on the right (includes an answer using `reduce`): http://stackoverflow.com/questions/6393943/convert-javascript-string-in-dot-notation-into-an-object-reference – nnnnnn Sep 28 '11 at 13:30

string as object reference to object variable

2 Answers2