Convert object to type given by string or typeof(number[])

Question

i like to convert a type given by a string, because i want to convert a string of numbers to an array of numbers.

var myStringType = "number[]";
var myString = "0, 0, 0";

var myStringArray = myString.Split(","); <- these array need to be a array;
var myNumbersArray = ConvertToAnyByString(myStringArray, myStringType);

I can convert by knowing the type, if the method above is not possible. Is there something like compare against typeof(number[])

Update: I think here is a misunderstanding. I don't know which type will passed to my function. I need type check that or convert it by a string information which type it is. And there is no way to do that natively in javascript, because there is no type of arrayOfStrings there is just a array. But i can make a helper functions to do this by hand.

Not sure what you're trying to ask but if you do '0,0,0'.split(',') that'll actually give you an array ["0", "0", "0"]. — Rishabh
– Rishabh, Commented Apr 13, 2013 at 3:17
@Rishabh I've a string and it need to be a number array not a string array. — MR.ABC
– MR.ABC, Commented Apr 13, 2013 at 3:18
You need to clarify 2 things please: * Do you expect to always have numbers in the array, or do you need to filter out errors (empty slots, text)? * Ints or Floats? — tomByrer
– tomByrer, Commented Apr 13, 2013 at 3:22

Rishabh · Accepted Answer · 2013-04-13 03:21:10Z

2

OK. try this -

var str = '0,0,0';
var arr = str.split(','); // ['0', '0', '0']
var int_arr = arr.map(function(el) {return parseInt(el, 10);}); // [0, 0, 0]

Hope that helps!

answered Apr 13, 2013 at 3:21

Rishabh

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3 Comments

tomByrer Over a year ago

Sure the OP expects only Ints, & not Floats?

GitaarLAB Over a year ago

note that prototype map on array is new ES5 and thus not browser-compatible at all. Also, the shim needed is quite big.

Ja͢ck Over a year ago

@GitaarLAB we can't all dwell in the past :) besides, the shim can be made quite small.

GitaarLAB · Accepted Answer · 2013-04-13 05:11:34Z

0

Based on your comment you can do (without .map or shim for .map):

var str = '0,1,8';
var arr = str.split(','), L=arr.length;
          while(L--){arr[L]=Number(arr[L]);}
//now arr contains numbers.

here Number(arr[L]); is the 'payload' but you also could use (depending on what you need):
parseInt(arr[L]); or parseFloat(arr[L]); or arr[L]*1; or even simply +arr[L];
as a payload. It's just what floats your boat.

test with: alert(typeof arr[1]); // number

But to actually answer the question that you originally asked (convert values in a array to a different type specified by a string), I offer this simple example to give an idea how one could do this:

var convertArrToAnyByString = function(arr,converTo,rad){
   var L = arr.length;
   rad = rad||10;  // optional, defaults to 10 as radix
   switch(converTo){
     case 'number':
        while(L--){arr[L] = Number(arr[L]);}
        break;
     case 'string':
        while(L--){arr[L] = arr[L].toString(rad);}
        break;
     default:
        arr=false;
   }
   return arr;
};

var str = '0,1,8';
var arr = str.split(','); 

// testing:
alert(typeof arr[1]);  //arr[1] should be string by default
arr=convertArrToAnyByString(arr,'number');
alert(typeof arr[1]);  // number
arr=convertArrToAnyByString(arr,'string');
alert(typeof arr[1]);  // string again
alert(arr[2]);         // still 8

You can easily expand on this example by adding types and even error-checking.

Good Luck!

edited Apr 13, 2013 at 5:11

answered Apr 13, 2013 at 3:34

GitaarLAB

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1 Comment

GitaarLAB Over a year ago

@Jack: thank you for the kind nudge. I've converted from lower case l to uppercase L just last month and missed that last l. Updated answer. Yes, tested.

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