Javascript Enum To Corresponding String Value

Question

So I have this in the javascript for my page:

var TEST_ERROR  = {         'SUCCESS'   :   0,         'FAIL'      :   -1,         'ID_ERROR'  :   -2       }; 

And perform tests on functions in the page like so:

function test() {     // Get the paragraph from the DOM     var testResultParagraph = document.getElementById('testResult');      // Check the paragraph is valid     if(!testResultBox)     {         // Update the web page         testResultParagraph.value = TEST_ERROR.ID_ERROR;         return TEST_ERROR.ID_ERROR;     }      // Something to store the results     var testResult = TEST_ERROR.SUCCESS;      // Test the calculation     testResult = testCalculate()      // Update the web page     testResultParagraph.value = testResult;      // The test succeeded     return TEST_ERROR.SUCCESS; } 

The result of testCalculate() and the value of the paragraph will be either 0, -1, -2 depending on the outcome.

Now I want to map this to a string so that the paragraph shows 'Success', 'Fail' or 'ID Error'

I could do this a few ways I have figured:

var TEST_ERROR  = {         'SUCCESS'   :   {VALUE : 0 , STRING: 'Success' },         'FAIL'      :   {VALUE : -1, STRING: 'Fail'    },         'ID_ERROR'  :   {VALUE : -2, STRING: 'Id Error'},       }; 

would require a modification to the enum dot accessors, or

var TEST_ERROR  = {         'SUCCESS'   :   0,         'FAIL'      :   1,         'ID_ERROR'  :   2       };  var TEST_STRING = [         'Success',         'Fail',         'ID Error'       ]; 

Which would require changes to the logic (result > TEST_ERROR.SUCCESS seems wierd tho!)

My question is how would you go about mapping an enumerator value to a string value in Javascript? I'm thinking the second way is the most sensible, but would like the enumerator to be positive for successes and negative for fails. I also like the idea of the first containing the strings and values in the object structure.

Any ideas?

Thanks!

Matt

PS. I'm going to be doing the testing in a Web Worker, so that the page doesn't hang and the results will be put into a table, not a paragraph like above.

PPS. I'm pretty new to Javascript programming, but do a lot in ASM, C, C++, C#.

Answer 1

Do you actually need the numeric values at all? If not then you could use something like this:

var TEST_ERROR  = {     SUCCESS  : 'Success',     FAIL     : 'Fail',     ID_ERROR : 'ID Error' }; 

Answer 2

Not quite optimal, but the cleanest you can get without pre-computing the reverse dictionary (and besides, this shouldn't be too much of an issue if you only have a few enumeration values):

function string_of_enum(enum,value)  {   for (var k in enum) if (enum[k] == value) return k;   return null; }